My Thai wife is now a US citizen but she always enters Thailand with her Thai passport. No lines and we breeze thru with me following. Bring the old Thai passport and get it renewed in Thailand. Someday that will come in handy. Believe me.
I know Thailand allows 20K but leaving the USA with more than 10K UNDECLARED is a problem.
It's legal to travel with more than $10,000 in the United States and abroad. You have the right to travel with as much money as you want. However, during international travel, you need to report currency and monetary instruments in excess of $10,000
Yeah. Fast track at the Airport, tip for driver 200 baht. Change a couple days expenses at the Airport to get by, then you’ll find money exchange out in town that give a better rate.