Good Date For Boyfriend's Birthday
I think a good idea would be to treat your boyfriend to a steak dinner. You will spend a bit more than you might at the Cheesecake Factory but the meal will be far more memorable. There are a ton of posts if you search the boards but my personal favorites are Chicago Chop House for an older clubby feel or The Capital Grille for a more modern setting. Both restaurants serve outstanding meat.
Hugo's Frog Bar for steak and seafood would be ideal and very memorable...on the expensive side though. Hugo's shares the same kitchen as Gibsons. If weather permits, then get seated outside where the views for people watching are fantastic. Chicago Chophouse serves up some of the very best steak in the city but the atmosphere and side dishes do not hold up to Hugo's.
Santorini in Greektown serves up some of the very best Steak, Lamb, and seafood. The atmosphere is elegant and serene but not stuffy. This place is perfect for a romantic birthday dinner.