Just went through BKK. This is what they asked for:
* passport (duh)
* flight ticket/boarding pass for the incoming flight
* thai pass
* negative pcr test
* T6 form (this was given to us to fill out on the plane)
* visa
* paid hotel confirmation
My visa and hotel confirmation were only wanted by immigration, but everything else I listed was asked for at pretty much every stopping point. I'm going to confirm other reports about the whole thing being a very easy, breezy process - they have tons of people out on the floor directing you where to go on top of physical barriers herding you to the right places. Everything moved very smoothly. From stepping out of the plane to grabbing my luggage, I'd say it took maybe ten minutes. They didn't give a shit about my covid test having been taken four days before my arrival, and they didn't ask about any onward travel (maybe because it's on my visa somewhere that I provided it? idk).
When you get out of the airport keep your passport and pass out, I've been asked for my passport like three times by hotel-related staff. Also the hotel check-in lady wanted to keep my Thai Pass; I had to ask her to make a copy because I only brought the one print out. The hotel I chose (The Green View) does their test on site immediately after check-in; it was administered around 1:30PM and she told me the results would come in at 1AM.
TLDR : Answer Summary
Upon arriving at Bangkok airport, travelers need to present several documents, including a passport, flight ticket or boarding pass, Thai Pass, a negative PCR test result, a T6 form provided during the flight, a valid visa, and a paid hotel confirmation. The immigration process is reported to be smooth and quick, with additional checks for the passport at various points in the airport and by hotel staff. Recent updates indicate that there will be changes to quarantine regulations starting December 1st for fully vaccinated tourists.
