I don't know if anyone will care, but I saw Grand Rapids, MI mentioned so I thought I'd throw my 2 cents in. I like taking Amtrak to Chicago from Battle Creek, MI. Usually about 3 hours, and that's my preferred way to go to Chicago for the weekend or longer.
Day trips are more interesting because of the South Shore Line.
It's a electric rail that runs from South Bend, IN to Millennium Station in Chicago. Take something like a Cubs game. I drive 2 hours to the Dune Park station
From there I park for free and ride the train to Chicago and then hop the Red Line to Wrigley. Even if it's a night game I can still make it back to Millennium Station for the last train out at 12:45AM.
The South Shore Line is also great for conventions on the weekend because it stops right at McCormick Place.
