An excellent place to tour with your kids. An interesting look at home travel was when the rails were more prevalent. Had a conductor there that worked with the railroad that showed what the different punches meant on your cards. Was very interactive with lots to see.
My son went through a huge train period and this museum fit the bill-we went several times. Our favorite part is the vintage rail cars you can go through and "drive" the train. This is a fairly small museum, but we would easily spend an hour just in the rail cars and toy train display. Its a great thing to do on a cold wintery day.
This is inside Union Station, which also houses Science City, the IMAX, and Planetarium. Check their website to find out special price dates throughout the year (when you can combine some of the Union Station experiences for a discount, or Science City Free Day so you can go there free afterwards).
Union Station is also across the street from Crown Center so this Rail Experience can be combined with Kalediscope (free) for a very family affordable outing.