As pm1stnau says "Hey, it's northern Michigan, you can't go wrong!!!". IMO, that's 100% correct. I think the UP is one of the most desirable places you can visit - in the summer after fly season. It's all rugged country with no big cities, which is appealing to us. Also, Michigan does a great job of maintaining its state parks (clean and in good repair) and really treats tourists like they appreciate the business. Check out Michigan's SP website (you probably already have) and you will find plenty of great places and attractions.
A great trip if you have the time is going across on the southern or northern main route, and then returning on the other. We like to camp on Lake Gogebic on the west side because we like to fish there, and it's relatively close to Black River Falls (excellent day trip) and Lake-In-The-Clouds. It's a lake left behind by a melted glacier that was trapped in the Porcupine Mountains.
If you go to the east side, Tahquamenon Falls is not-to-be-missed. We camp at the Lower Falls CG because it centrally located, but in season it usually gets full. The River Mouth CG is much quieter, but farther removed. If your near Tahauamenon Falls, Whitefish Point is close. If you go there, you travel through Paradise, MI, and that's where Brown's Fish House is located. Brown's is a small family restaurant that's outstanding. We have never been to the locks at Sioux, but that's something we plan to do next trip.
Another place we really liked was Kitchitikipi near Palms-Book SP (south-central). Kitchitikipi is a Native American word for big spring. It has to be seen to be appreciated.
Kim, I'm glad you asked about the UP. Answering your post has got me excited to plan another trip there.