This is worthless for out-of-towners with limited reference points. Actually, I've gotten a similar request from an out of towner staying near Millennium Park and had to use search because I don't go downtown that often. I found it difficult to sort through a bunch of dead-end threads and I've lived here my entire life.
I'll throw out a few places I gave my contact and you can google the addresses or use search here to learn more:
Mercat a la Planxa - Tapas
The Gage - Gastropub
Frontera Grill - Mexican (in River North but not a bad cab ride)
Purple Pig - On Michigan Ave.
Bin 36 - wine/cheese flights with full dinner menu (in River North as well)
Shaw's - seafood (River North)
Steak - there are a ton of these - Gibson's (typical Chicago steak in Gold Coast), Keefer's (River North) Primehouse (River North).
Hope this gets you started, if you don't find what you're looking for in this list, reply back with more info.
"It's not that I'm on commission, it's just I've sifted through a lot of stuff and it's not worth filling up on the bland when the extraordinary is within equidistant tasting distance." - David Lebovitz