Don't even know where to start, one day is def not enough to stay or do the town justice.
For one night in town I'd probably hit a museum or see a play, (the chicago art museum is awesome, one of the best in the country) blue man is cool if you never seen it before, plenty of great food places and bars on Rush street. Gibson's, Tavern on Rush. Uno's Pizza is not far away, famous shopping on the mag mile etc etc.
Plenty of museums as well but if you were only doing one museum do the Museum of science and industry, its nice.
The planetarium, shed aquarium, Field museum, millennium park, Soldiers Field, Buckingham fountain (not on in winter)are all walking distance from each other,
Sears tower (the big willie) has that glass floor that extends over the building side on the observation deck.