Dairy Queen is nice for a summer treat! It's in the "official" pedway by the First Chicago (now Chase, I guess) building.
I guess I never thought of the places previous posters have mentioned as being in the pedway. Those places are in what my co-workers and I always called "the concourse," or the whole underground maze under Boulevard Towers, the Prudential Building, One and Three Illinois Centers, etc. My own definition of the pedway is the maze that runs from from under the Fairmont all the way to to Illinois Center and a few other places.
Anyway, it's all in the semantics, huh?
A ton of people I know love Jaffa Bagels (in the concourse between Boulevard Towers and the One Illinois Center) for their turkey sandwich lunch special. I'm a vegetarian so I can't vouch for it. But it seems like a deal!