I grew up in MI (greetings fellow CMU grads!) and am surprised no one has mentioned Holland, MI on the lower west side. The Tulip festival is (or was) in early May, but it's a great stop to see the Dutch influence in that area. If you're going into Amish country in northern Indiana and you're football fans you have to stop in South Bend to see the most beautiful university campus there is- Notre Dame! Yes, I know U of M and MSU are great- but you can't beat the sun glinting off the Golden Dome and the multi-storied mosaic of Christ. The campus is at it's most breathtaking in the fall, but so beautiful any time of year. Enjoy your travels!