I kind of think that if you're coming for less than a year, you (and specifically your wallet) would be better off coming in on a triple-entry tourist visa. Not exactly sure about the States but when I came in from Canada I got a triple entry visa (3 * 60 days for a total of 180 days) for about $100?
If you go through a school you're looking at paying about 20,000 baht for a year (about $700) and you won't even use it all. You'll also have to go through the hassle of paperwork and immigration visits. While you're here, you might be interested in seeing Laos or Cambodia or Vietnam for a couple days that you can fit in with your visa runs. You'll also be more free to move around and change camps without being tied to a language school in a specific part of the country.
Just some food for thought.
