Milky Way is our favorite vegetarian spot in Pittsburgh. It does have a cafeteria-style feel and it can get busy on Thursdays and Sundays, but you can't do better if you're looking for American-style food.
The sandwiches, paninis, and hoagies are all consistently great, and you don't miss the meat. They have good falafel and fake chicken with plenty of texture and flavor. They also have great milkshakes and sides. The sweet potato fries and its "secret" sauce is a favorite, with a nice crunch and a good mix of tangy and sweet. And the salad bar is the best! You get a wide range of vegetables, cheese, and dressings, and the salads are large enough to feed two or three.
If you're looking for vegetarian-friendly comfort food or a good salad, then this is the place to go. It's also worth trying if you're not vegetarian or keeping kosher, if just to see what they have to offer.