In Thailand the best ways to exchange money are ATM Card, Credit Card, Travelers Checks, Cash. However each method has advantages, disadvantages and things to watch out for. Carefully check out any transaction and make an informed decision. (Source: http://www.thaivisa.com/thailand_banking.0.html)
 
Thailand\'s ATM system is not always the most reliable, and machines are often down especially in the provinces. Therefore, it pays to plan ahead and not to be entirely dependent on your card. (Source: http://www.into-asia.com/thailand/faq/money.php)