there's some excellent traditional chinese restaraunts on Olive. Lulu seafood restaraunt has a very authentic dim sum on weekend mornings; I'm sure the rest of the food is equally good. There's a review in sauce magazine about it.
House of Wong isn't bad, but it's more "american" chinese food.
If you want to get embarrassingly intoxicated with your meal, Guo Bin at 170 and delmar has giant drinks and not-so-shabby food.
The thai food in the loop isn't awful, but IMO it's a bit pricey for the quality of food that you get.
I second the recc for Everest -- I haven't been to the new place yet, but their old location was a bit "hole in the wall" and delicious. The owner came over and talked with us; apparently they're the only Nepalese restaraunt in the midwest. If you care, they also have tons of veg options.
If vietnamese is what you're looking for, also at delmar/170 is Mai Lee, which is also pretty authentic and very good.
PF Changs by the Galleria, Yen Ching on Brentwood Blvd....the best "Asian" spots are scattered all over with a good mix of Thai, Vietnamese and Chinese on South Grand Ave. There is another large Chinese population on Olive Blvd. just east of I-170. There is the loop (which may be closest to Richmond Heights) and they have a good selection of Thai and Vietnamese. House of Wong in Clayton is the only one I know of in Clayton proper.