-visit top of Hancock/Sears towers
-maybe take an architecture boat tour if its not too cold
-go to museums: Art Institute, MCA, Smart Museum, Museum of Contemporary Photography, International -Museum of Surgical Science (really creepy), Museum of Science and Industry. Maybe your visit will coincide with the first friday of the month in which case you can hit up the galleries in the west loop and get drunk on free wine.

Most importantly, get out of the loop. Chicago is made up of tos of different neighbohrhoods each with a different feel. Check out Hyde Park, Logan Square, Wicker Park, Rogers Park, Bronzeville, Pilsen/Little Village. Eat the diverse selection of foods to be found in these neighbohrhoods. I've left so much out. If you have any specific questions PM me or go to chifg.com. Have fun.