I'm from Denver, CO. Just fly here, bring copies of your passport in case, bring record of vaccination (not really a requirement right now in Thailand, but you might bounce to another SE Asia country), and have a return flight booked and able to show immigration.
They're probably not going to ask for anything, but those are the things I'd bring. No need to announce your visit. 2021 was quite different. Now it's easy. Don't sweat it.