Hi Andy
I used baht when I was in Thailand. You should be able to order it in advance or buy it at the airport. Dollars are often acceptable but sometimes they might not be, especially for smaller purchases. Also, you will end up paying more if you use dollars, as vendors will be rounding up their prices.
So far we have four bookings for this holiday (two men, two women) and I would expect this number to rise before you travel as there are still four months to go.
Kind regards,
Olly, your editor