Passport to use

Only thing I can see :
- check for each embassy their fees and location in Bangkok, like for affidavit for retirement income, passport renewal, notary services, and others services they propose
- check where in Thailand they have consular, like sometimes in Chiang Mai if you live far from BKK
- Regarding treaties : double taxation, extradition, etc... both countries have signed them
- But American citizen have a real advantage regarding business link to the Amity Treaty ( just google it ), they can own it 100% without having a Thai majority usually 51%, but the process can be long to go through. But if you are just retired you are not looking to run a business on your own as you can not work with a retirement visa
- For some visa or work they can ask like a police check or criminal record check and up to you to see in which country you can get it more easily..