When I knew I was moving to Chicago, I looked into the city's history, including reading Erik Larson's masterpiece, 'Devil in the White City.' So much of my trip to the Museum of Science and Industry was motivated by experiencing the science museum and seeing the Palace of Fine Arts building.
I don't think it matters what you're going there for, it is going to be a good time. I had a blast. Short of the Body exhibit, I saw and did just about everything, including an up-close look at a U-505, admiring baby chicks and watching an avalanche.
I also stopped by the Osaka Japanese Garden, just a little south of the museum. Another piece World's Fair history, its a wonderful little escape from the city scape of Chicago's south side.