If you work or live in the Clayton area, I highly recommend the Blackberry Cafe on Forsyth next to the metrolink station. I have eaten there two days in a row (I am out here for training). The first day I had a spicy tuna wrap which was excellent. And today I had the soup and salad combo with chicken tortilla soup. Originally I had stopped in for a gyro but everything else sounded so good I had to try it. I may still get my gyro when I'm back monday for more training.
The service is very friendly. It is run by the owner and his wife. If it's your first time in he'll happily tell you all about the place and it's specialities. Also, Wash U employees get a discount!