I agree about learning the Thai script. In fact, I do read and write a bit of Thai. I decided to study the Thai script because that was the advice given me by the foreigners I met who (I thought) spoke the best Thai. I was a bit half-assed about it for the first few years. It's only now that I'm really putting in some consistent effort (about an hour a day, sometimes more). I find that I'm able to practice a bit while at work because everyone in my office is constantly emailing each other memos. If I have a bit of time, I'll practice translating/reading those. In my free time, I send text messages to friends and chat on MSN. My typing in Thai is godawfuly slow but it's still fun.

I started studying seriously again because, as the person above wrote, transliteration just doesn't cut it. I use two different sources for the majority of the "looking up in the dictionary" I do... one of them is Thai to English dictionary & transliteration. The other is the Thai for Beginners book from Paiboon Publishing. There are probably some others, too. They both use different systems for transliteration. And then there's the official transliteration system. Unfortunately, I don't know all the tone rules and while I can sound out the words, there's often something screwy. For the tones and some pronunciation tips I consult the sources. Or I just ask people, but if there's no one around...

Learning the transliteration language is almost just as much work as learning the Thai script. Might as well learn the Thai.