1 week on the chart in The Netherlands (April 10, 2022)

There's been much talk about BL's potential as a driver of tourism. And it's evident, as some of you have shared your stories here in this sub, while others have asked for help planning upcoming trips. But there still appears to be a lack of easily accessible information for people visiting Thailand for the BL. Here's an attempt to remedy that, with this guide to visiting Thailand for BL fans. I've taken the liberty to incorporate suggestions from several previous threads here, as well as various other sources, so thank you to everyone who's contributed to the discussion.

First things first

This will only touch on things specifically of interest to BL fans. For the other aspects of your trip, including most basic planning stuff, please consult the usual travel resources.
That said, firstly you'll want to consider the purpose of your trip, and how much of it you want to dedicate to BL stuff. Do you just want a regular vacation, with a side stop for some merch, or are you here to relive the all the scenes from your favourite BLs? It's very possible to come up with a weeks-long itinerary of nothing but BL locations, and you could spend as much time mall-hopping to catch artist appearances, but Thailand also has a lot of other things to experience, whether you want to stick to the major attractions or go off the beaten track. It's all up to you.
Also, this probably goes without saying, but if you want to attend a specific event, be sure to plan around it and make travel arrangements accordingly. Concerts and fan meetings usually have tickets go on sale a couple of months in advance at most, so you'll want to have flexible options if you book your travel and accommodation before then.

Destinations

Most of the BL-related things you can do will be concentrated in Bangkok, so it's where this guide will be mainly focused, but there are also several provincial locations that have featured in BL, especially Chiang Mai and Chiang Rai in the north and Phuket in the south, all of which are major tourist destinations in their own right. Series have also spent time at plenty of beaches and resorts (particularly around Hua Hin and several towns in Chonburi province) as well as other popular excursions, most of which are short trips from Bangkok. Further out are the island resorts of Koh Samet, Koh Tao and Koh Lanta. The north-east Isan locations are rather off the tourist trail, but could well be worth the experience if that's your style of travel.

Getting immersed

Arriving in Bangkok, one of the first things you'll notice as a fan of Thai BL (or Thai dramas in general) is that you're surrounded by familiar faces everywhere, on banners and billboards and the back of tuk-tuks. Although BL actors aren't that well known among the general public (a surprise to some), the better known ones have a ton of brand endorsements and appear in ads for all sorts of products. Even if you're not planning your trip around BL, spotting actors you know in ads and fan projects can be an entertaining pastime.
Head into a 7-Eleven and you're pretty much guaranteed to see faces you recognize, perhaps on products you're already familiar with from all those series sponsorships and product placements. If the advertising worked and you're dying to know what that bottled green tea or that seaweed snack tastes like, this is your chance to give them a try.
Speaking of tasting, you'll probably be sampling plenty of Thai food while here, so why not include some of the food and drink items from the series you remember, be it som tam from What Zabb Man, the traditional desserts from UWMA, or the famous pink milk, known here as nom yen?
Meanwhile, if taking public transport, spend some time watching the people and see how BL imitates real life. Do you recognize the colours of the school uniforms? Or the university students in their white shirts and black slacks? You might even come across some engineering students in their workshop overshirts.
If you miss hearing the Raikantopeni disclaimer at the beginning of shows, be sure to turn on the TV to catch it as they air live. Be aware though that following shows in Thailand will be more difficult than at home, as they won't have subtitles on TV or on most local streaming services, so you'll likely need a VPN.

Merch stores & fan hangouts

This might be a bit of a letdown, but apart from GMMTV's, there aren't really any physical stores for official merchandise. But since you'll be in the country, you could check with your accommodation to see if they can arrange to accept local package deliveries for you, so you can place some online orders and avoid the international shipping fees. Be sure to check the processing and delivery times - this might be tricky (and won't work with pre-orders, only in-stock items).
GMMTV's shop is not a traditional giftshop as one might assume, but more like a kiosk at their office on the 30th floor of the GMM Grammy Place building - there's just a small product display and a cashier window. Apart from buying products, there's a good chance of running into some actors when visiting, though you're not allowed to linger and there's nowhere to hang out apart from some cafés on the ground floor. You will likely spot some fan-project displays (as mentioned above) outside and in the building, and the cafés will often have cup-sleeve giveaways by fans. Here's a very helpful guide by u/snuffles005: How to visit the GMMTV building and shop
Elsewhere, there's Wab Cafe' and Friends, by the Studio Wabi Sabi people. It's a café, so you'll be buying drinks there rather than merch, but it's very much a space created for fans, and there will often be something going on like fan projects and giveaways, or maybe mini-events with actors making an appearance. It's in RCA, Bangkok's main clubbing neighbourhood (and home to studios where many productions hold their workshops), which takes a bit of an effort to get to, but it's also probably the most dedicated hangout space for BL fans there is.
From Star Hunter, there's Hunter Village, a studio space (mostly used for dance classes) in MBK Center, one of Bangkok's most popular malls. It's a mostly open space, so you'll be able to see if there's someone coming in or something going on, but I'm not sure if it's really somewhere you can hang out at.
Other than that, quite a few actors have their own cafés or some other business, which you might want to visit to support them directly. Clothing and fashion items (perhaps from brands with your faves as presenters) may also be something you'd want to go shopping for.
For manga and anime (including BL/yaoi) there's an Animate store (the specialty chain from Japan), also at MBK Center. In addition to imported works, they also have an extensive Thai section, with both translated and original works.
If you want to observe the Thai novel scene, just walk into any major Thai book store, where you'll likely find rows, maybe entire shelves, of BL novels, prominently displayed - BL has very much gone mainstream in the Thai publishing industry. You'll also find glossy magazines featuring actor photoshoots here. You'll have less luck finding English translations, though, as most translated works are e-book only. For English-language (and Japanese) books in general, your best bet is Books Kinokuniya. They do have Japanese and Chinese translations of some Thai BL novels, as well as the English manga versions of SOTUS and Manner of Death, at international prices.

Catching events

Seeing actors up close (or at a distance) in real life will probably be the BL highlight of your trip for many of you. And unless you're ultra specific as to whom you want to see, there are ample opportunities to catch these actor appearances.
The biggest experiences will of course be the major events - concerts, fan meetings, and the like - that you'll have to buy tickets for. As mentioned above, you'll have to plan around them if you want to attend (which also limits how long you can plan in advance), and make sure to actually get those tickets. They're usually announced very publicly, so it's hard to miss them if you follow the usual news update channels. If you're around when one takes place but can't attend, it can still be worth dropping by if you want to get hold of the merch or just check out the crowds.
For more casual fans, you'll still have plenty of chance to see actors at smaller events, as there's pretty much always something happening somewhere, though there might not be much choice on who you get to see. These events vary a lot in scale, and can be anything from product launches to movie premieres. Most artist's agencies will announce them on their social media channels, usually on a weekly basis, and fan accounts may help share and/or translate them. You'll have to follow them to keep updated.
Most of these events will be held in Bangkok's plethora of malls. The biggest ones are mostly lined along the BTS Skytrain's Sukhumvit Line, so if you plan to do a lot of mall-hopping, whether for events or just shopping, consider getting accommodation with easy access to the BTS for convenience. Here's a great post by u/BumblingWombat that describes the experience in detail: What it's like to go to BL events in Thailand (Oh yeah, there are also top-spender events, which I won't go into, as I don't know anything about them. Those who're aiming for them probably won't need this guide anyway.)
Aside from these specific events, there are also annual book fairs that are partially or directly BL-related, where actors from various agencies may make appearances. The mainstream National Book Fair and Book Expo are usually held at the beginning of April and some time in October. Since last year, BL novels and publishers have had a large presence there, and GMMTV actors made daily appearances with fan gatherings in the car park. There are also smaller book fairs directly focusing on BL: Y Book Fair in July, and International Novel Festival at the end of November. They also feature actor appearances, but can also be worth seeing just for the atmosphere if you're interested in experiencing the literary BL scene here.
On the other hand, to experience more of the community side of the fandom, you might want to check out some fan-held events, such as the birthday projects that fan clubs often do, which may be in the form of café galleries or mini-gatherings. Info will mostly be on Twitter, though it may not be readily translated.

Visiting filming locations

If BL inspired you to make the trip to Thailand, no doubt you'd be interested in visiting some of the filming locations yourself. But while some of them are traditional tourist attractions in their own right, most aren't normally on the radar for general visitors, so it'll take a bit of investment (in time and travel) to include them in your trip.
If there's a single most iconic location to recommend, it must be the Rama VIII Bridge over the Chao Phraya River, which shows up in more BLs than anywhere else. So far, it's been seen in SOTUS, SOTUS S, Gen Y, Tonhon Chonlatee, I Promised You the Moon, My Ride, Enchanté, Cutie Pie, KinnPorsche, Even Sun, 2 Moons: The Ambassador, and Boyband. It's not really a tourist attraction, but it's a major landmark of modern Bangkok that everyone knows, and isn't too hard to get to. It's a bit of a walk (some 15 minutes, or just take a tuk-tuk) from either the Phra Athit or Thewet Pier if you're coming from the main riverside attractions and use the Chao Phraya Express (or Tourist) Boat. If you're into financial history, the Bank of Thailand Learning Center and museum is right next to the bridge. Otherwise, Suan Luang Rama VIII Park by its base is also nice, and also a filming location. The bridge itself is most photogenic at night, but make sure you have transport back if you stay late. Consider one of those dinner cruises if you want to experience it from the same angles as KinnPorsche and Cutie Pie.
For other locations, you'll need to do some research. If there's a specific series you want to follow, try searching to see if someone has already compiled a list of locations, which is likely the case for the more popular series. Most info will be on Tumblr or Twitter.
Filming locations may be public places, shops and businesses, private establishments, or purpose-built or converted studios, so remember to think of their ability to welcome visitors. Dress appropriately for the venue, take care to respect their regular functions, and be considerate to other people. Some of the most familiar locations are university campuses, and the grounds will generally be open to the public, but they're not usually equipped to deal with large numbers of visitors. So if you do visit, have fun reliving those memorable scenes but make sure not to disturb the real students who are there for class. Meanwhile, cafés, bars and restaurants would surely welcome your patronage, but please do not snoop around private offices or people's homes. It all boils down to following common sense, really.
A lot of the locations will be quite spread out and some distance away from downtown, so you'll have to plan carefully if you want to hit more than a few. You might want to hire transport for the day, but also take the traffic into consideration.
If you've always wanted to sleep in the same room that your favourite characters lived in (or at least an identical one), you might be in luck. Some of the apartment locations may have rooms available for daily renting, so check with them. As above, though, their location can be rather inconvenient transport-wise. On the other hand, you might want to opt for the hotels and resorts that featured as locations, which will be better equipped with tourist facilities.
For houses specifically, I have a post on The houses of Thai BL. Most of them are private property rented out as studios, but some will be happy to accept visitors (for a fee) on their off days. Contact their management to see if a something can be arranged. Or if you're serious about it and ready to pay, just rent the place at full price for your own personal photoshoot. If you try it either way, do let us know how it turns out. On the other hand, Wawa House (To Sir, With Love) has a café for visitors, Slōlē (Golden Blood, Bite Me, Enchanté, The Tuxedo, The Eclipse) is a real-life café when not filming, and Red Brick Kitchen (Not Me, KinnPorsche, War of Y) features a chef's table dining experience (reservations only, 4 persons minimum).
If you're just looking for some usual attractions that happen to have BL appearances as a bonus, here are a few (very non-exhaustive) suggestions for Bangkok:

• Temples & shrines
  • Wat Arun (KinnPorsche)
  • Wat Kanlayanamit (KinnPorsche)
  • Rong Kueak Shrine (Our Skyy: Pete-Kao, Our Skyy 2: Never Let Me Go)
• Museums & art galleries
  • Warehouse 30 (Theory of Love)
  • Bangkok Sculpture Center (Vice Versa)
• Historic buildings
  • Hua Lamphong Railway Station (Theory of Love)
  • So Heng Tai Mansion (Our Skyy: Pete-Kao)
  • Neilson Hays Library (Enchanté)
  • The House on Sathorn (functions as a restaurant) (KinnPorsche)
• Zoos, aquariums & other activities
  • Sea Life Bangkok Ocean World (UWMA, IPYTM)
  • Flick Skate Park (Cutie Pie)
• Themed markets
  • Asiatique The Riverfront (Why R U?)
  • Kwan-Riam Floating Market (My Engineer)
  • ChangChui Creative Park & Plane Night Market (Vice Versa)
• Bridges & Parks
  • Rama VIII Bridge & Park (see above)
  • Memorial Bridge (& Chao Phraya Sky Park) ('Cause You're My Boy)
  • Bhumibol Bridge (& Lat Pho Park) (Not Me, KinnPorsche, LITA)
  • Chong Nonsi Skywalk & Canal Park (Chains of Heart, Bed Friend, The Promise)
  • Queen Sirikit & Wachirabenchathat (Rotfai) Park (Cutie Pie, My School President)
  • Benjakitti Forest Park (Vice Versa)
  • Suan Luang Rama IX Park (Vice Versa)
  • Chulalongkorn University Centenary Park (Vice Versa)

While Bangkok's malls are very much major attractions by themselves, I didn't include them as their appearances are quite too numerous to list.
Outside of Bangkok, each series will mostly feature locations relatively near each other (except Cupid's Last Wish, which went all over the country), so I'll just list the series by destination without going into each location's detail.

• Chiang Mai: Manner of Death, Triage, Dew, Grey Rainbow, Sky in Your Heart, On Cloud Nine, 180 Degree Longitude, A Tale of Thousand Stars, everything by Wayufilm
• Chiang Rai: A Tale of Thousand Stars, The Love of Winter
• Lampang: Bed Friend
• Khon Kaen: Love Mechanics 2022
• Chachoengsao: Remember Me
• Chonburi: KinnPorsche, Star in My Mind, Never Let Me Go, Moonlight Chicken, Cutie Pie (Bira Circuit), My School President (Institute of Marine Science)
• Koh Samet (Rayong): Hard Love Mission
• Amphawa (Samut Songkhram): Together With Me
• Kanchanaburi: UWMA
• Hua Hin & nearby (Prachuap Khiri Khan): Bad Buddy, My School President
• Koh Tao (Surat Thani): Even Sun
• Phuket: ITSAY
• Koh Lanta (Krabi): Why R U, Why You... Y Me?

Further resources & suggestions

The Let's Talk BL podcast hosts talked about their experience in Thailand last year, covering a lot of the above points over several episodes at the beginning of season 3. Be sure to check them out if you want all the details, especially S3 EP3: Tips & Tricks for the perfect BL experience in Bangkok. Some of their main tips that I didn't mention above are not to overstretch yourself trying to go to everything, and to use a map to plan your days.
Colourme-feral on Tumblr has an incredible Google Map that plots locations from several series, and more in their blog, which a lot of the above is sourced from. For Bad Buddy specifically, Telomeke-bbs on Tumblr has a series of posts that analyse the locations at an insane level of detail.
I'm sure I haven't covered nearly everything in this post, so please feel free to add your suggestions in the comments. (I'll try to expand the locations list as I get around to digging for more series.) If you have questions or need help identifying a specific location, feel free to ask! (Though no guarantees there.)
For full disclosure, I'm receiving no compensation whatsoever for writing this. Any biases or omissions are purely unintentional.