Sweet Basil just recently opened up downtown, and it is by far the best Thai place in the city. They have a unique style of preparing the food that makes the experience so enjoyable.
Try the thai iced tea, which comes in a huge glass that looks like a tower. The pad see ew is probably my favorite, with lots of garlic and a sweet gravy sauce.
The ambience is the best part of this restaurant--bright colored lights, tables close together, and always bustling.