Everyone loves Salad King. It has lots of seats (which are pretty much always full) and as far as Thai food goes, it's very cheap.
Salad King is often lined up, with waits of up to 30 minutes, but people often choose to wait. They also do take out, but I've been told that take out could take up to 30 minutes, so if you are hoping to by pass the wait by doing take out, know that it's not always a safe bet. I would recommend that you call ahead, because it's really the best way to save yourself some grief.
Lots of their food is delicious, but my personal favourite is the Siam Noodle. It comes with a peanut sauce that is a reason in itself to buy this dish.