The east side of Lake Superior is stunningly beautiful. Cliffs dropping sheer into the water.
If you visit Sault Ste Marie, check out the bushplane museum.
You might want to consider taking the Lake Express ferry between Milwaukee, WI and Muskegon, MI if you want to skip traveling thru Chicago, IL.
Mackinaw City’s good too, if you like poking around in the touristy little shops. They also sometimes have stuff going on like live music at a bandstand in the middle of one of the shopping areas. Much less horse poop in the city than on the island, btw, if that’s something you want to avoid (or seek out, if that floats your boat).