Whenever I'm in Dallas, I try to make it a point to visit Club Schmitz. I enjoyed going there while in college, and I enjoy going there now. They have the best burgers, and I really like the atmosphere. The regulars are people from all walks of life and it's a great place just to people-watch if you enjoy doing that sort of thing.
Pros: Inexpensive, Neat atmosphere, Good parking
Cons: busy lunch