I've been to La's Thai a few times, since I work within walking distance, and haven't been disappointed with anything I've tried. They have a large menu with good lunch specials, friendly staff, and the food is good.
My benchmark for a good Thai place is Massaman Curry and La's version is excellent. If you like peanut sauces, this is a definite must try. The Thai iced tea is delicious as well.
It can get pretty busy around lunch time, but I've never had to wait too long for a meal. The dining area fits more people than you'd expect and manages to still feel like there's enough room.
I'm working on getting some co-workers to try it out next time I go; one can only handle so much cafeteria food.