I'm a bit late to the discussion, and I'm a vegetarian so usually bad at these kinds of things.
But my husband swears by the corned beef sandwich at
Manny's Delicatessen. I don't know what the rest of the scene is about, but Manny's is where all the movers and shakers in town go. Obama stopped by there during the transition; I think Mayor Daley and his family hang out there. I've never been there (not really a vegetarian's dream), but I'm sure my husband could give you a good description if you're interested.