Nobody has mentioned Gibson's yet?
Gibsons Bar & Steakhouse
Is it expensive? Yeah. Is it worth it? I think so. Great atmosphere, it seems a lot of famous people that live in or visit Chicago stop in there quite a bit.
If you can't get into Gibson's, or don't want to wait - go next door to Hugo Frog's (literally next door). Same kitchen, a lot of the same things on the menu. Similar prices. Obviously just as good.