Too many places to mention. Depends greatly on your interests and timeframe.
Flew my -7A into Mackinac Island this past Labor Day. Daily parking fee at MCD for single engine was $12.50. The extremely touristy downtown area was very busy with bicycles everywhere, most of which were parked along the street. Much to see cruising around the island on a bike. Toward the end, I got tired of trying to dodge the horse***t all over the roads, except in the downtown area where they kept it cleaned up pretty well.
Landed at St.Ignace (83D), where the airport manager was quite accommodating in line with the general openness and hospitality the UP seems to be known for.
Petoskey and Traverse City area are worth a visit, depending on your interests.
Landed at Ephraim-Gibralter (3D2), which allows camping on the field. Also has a courtesy car and bikes to use although there is a big hill to climb to get back to the field. Restaurants are unique and, while they don't seem plentiful, are adequate to service the visitors. The towns are very small, less than 1000 population, and really cater to well-heeled clientele from Chicago. Parking fee $16.
Green Bay Packer Hall of Fame at Lambeau Field is worth a visit, even though they are not my team. I've heard the FBO at GRB is rather accommodating.