Last minute trip to Thailand. Am I missing anything?

I am contemplating a last minute trip (next week) to Thailand. This would be my first time. I’m a US citizen, going for three weeks. My understanding is I do not need a visa. My passport doesn’t expire until July 2025, so I should be good there. When I went to Cuba, I had to purchase a special type of health insurance. Are there any insurance requirements like that? Is there anything I should bring with me, specific to Thailand, that I might be overlooking? And what/where is the best time/place to exchange USD to Baht?