The Custom House, Blackbird, Bin 36 for casual
Ed DeBevics for breakfast, a Chicago institution, food is more diner like, and 50's era sassy waitresses put on a show. I will try to think of more....
I second the Girl and the Goat
Adler Planetarium--a good addition to Deb's sites.
If you go the the Art Institute, be sure to see the Thorne miniatures. Fascinating. smileys/smile.gif
Chicago Symphony Center--great venue, I was lucky enough to see Itzahk Perlman, with Daniel Barenboim conducting. Scored a ticket same day as show. smileys/smile.gif Maybe someone interesting will be there when you are.
The downtown pier area is called Navy Pier. touristy, but nice spot on the water.