I'd be all about the history. Ronald Reagan was born in Tampico, IL and raised in Dixon, IL. I believe there are historical sites in both towns (and they're not all that far from each other). Springfield, IL is full of Abraham Lincoln sites - Lincoln's Home, Lincoln's Tomb, New Salem (where he lived before he moved to Springfield), The Abraham Lincoln Presidential Library & Museum. You could easily spend 3 days in the Springfield Area. Springfield is not at all a big city - only 100,000 people and very easy to drive around in.
If you'd like to see a major league baseball game, St. Louis, MO, is not far away. It's a bit larger than Springfield, but Busch Stadium is right off the interstate with very easy parking. It would be a great experience!