Must see in Michigan, Mackinaw & Great lakes area?

We'd like to make it to the UP in July-ish. We are B campers and basically need only elect. We'd like to stay at the Straits SP and further north. Any issues or problems with getting a site in that time frame? Any preferred state, COE or Federal parks in that area. And what must see (history, scenic, quaint, etc. Touristy type stuff without the neon lights nor T-shirt shops. Plus good local eateries and fish markets.)