You lucky so and so!!
Just a few suggestions from me
Good firework display on Navy Pier Weds and Sat evening in summer, very busy but nice atmosphere
River taxi from Navy Pier to Sears Tower, along Chicago River past lots of Skyscrapers - cheaper than an architecture tour
Shedd aquarium (including whale/dolphin show)
Millenium Park, near Art Institute -stunning architecture including Cloud Gate
Swimming off Oak Street beach with Hancock building and Drake Hotel in background
Baseball at Wrigley Field
A couple of record/CD stores Jazz Record Mart and Dusty Groove
Harry Caray's Steakhouse