Hotel Etiquette (1st time traveller)

[Oliver2]

Are there "single" rooms available in Thailand? I don't think I've ever come across one.

Following Mancs's advice, I'd add two points. Firstly, the most expensive 5* hotels may require a joiner' s fee. Secondly, holding a visitor's ID card is a good thing, providing you with security...and is particularly helpful for a newbie.
Gay hotels in Pattaya always did (do?) this, phoning when the visitor left to ensure all was well. It also enables reception to check that the guy is not under-age. This may be an issue if you use apps.