I think you might have to help us narrow this down a bit:
--By "Chicago-themed" I'm assuming you mean deep-dish and/or beef? Correct? (This could also be interpreted to refer to one of the many ethnic cuisines that are strong in, but not necessarily unique to, Chicago)
--Are we talking 10 people? 50? 100? A small party can go anywhere, the larger you get, the more limited it is.
--Budget? No need for an exact number, but is it "low budget", "medium", or "unlimited".
--Do you have to like the food? This is a serious question. When I was planning my rehearsal dinner, I grappled with the question of whether or not I actually wanted to eat there, or if the place was just cheap and could accomodate our party.
Sorry for the quiz but I could name about 40 places that might meet your original criteria.
Congratulations on your impending nuptuals and welcome to LTHForum.com!
Best,
Michael