The best & cheapest way to wire large amounts of cash to Thailand for Americans and to get the best exchange rate using a credit card.
If you are a veteran or a family member of one, you can qualify for NFCU membership. They are one of, if not the largest, credit unions in the world.
Wiring from an NFCU account to a Thai account, any amount of money, is a straight $25 wire fee. Depending on the bank, it will show up within 1-4 days. Always send US dollars as you will get a better exchange rate by the receiving bank in Thailand.
The best way to avoid any worries about Thai taxes, AND get the best exchange rate for dollar to baht, while racking up credit card reward points, is to use the NFCU flag ship VISA rewards card and not have the transaction on the radar. NFCU Visa gives you whatever the international exchange rate is at the time of your purchase, and you can use the credit card in most businesses that accept credit card.
I used to be a big fan of NFCU; however, their services have deteriorated since they opened up membership to branches. Regardless, if you are eligible, it can save you a lot of money. Drop a note if I can answer any questions.