HELP: Ideas Needed!!

We are going to Minneapolis, MN at the end of April to the beginning of May for a Church Planting class being taught by a professor from Trinity (where Daniel was accepted to Grad school and where we were going until we felt called to the mission field). Anywho, we have decided instead of flying (and renting a car when we get up there) to just leave a day and a half early and drive for 2 reasons (I am sure there are more I just can't think of them right now) 1. Money & 2. We love to explore and take road trips any chance we get, and what better time than now! So my question to you is.....Do you have any suggestions where we could stay/visit/stop/explore on our way to Minnesota? We don't have a "specific" way we have to go so we can detour a little! Our first thought was to stop in St. Louis and see the arch and get a hotel there...because we have never been, and that is about halfway. If you have any insights PLEASE PLEASE do share. I am even providing you with a map to get those creative ideas flowing!