I grew in Toronto, and worked in Ann Arbor, MI for several years so I have some insight into Michigan that might be relevant.
First of all, outside of Flint and Detroit, you will find that Michiganders take care of their properties. If you drive across the state, you won't find rural places and working class areas, with dead cars in their yards and overgrown lawns -- like in most of the rest of the US. This is something that I always found interesting.
If you are driving to SSM, and crossing at Detroit, you might swing by Ann Arbor. THere is a lot of construction but the downtown has a nice vibe as does the UMich State street area. Check out Frita Batitidos for some amazing street food, or Zingerman's if you can afford a $18 sandwich.
The West side of the state has Traverse City/Petosky which is a little like Gravenhurst/Muskoka but not really. This where the mid century rich people from Detroit would go on weekends. They are active cities that have a large summer vacation crowd. AS mentioned before Sleeping Bear Dunes is a very cool state park that has 400ft cliffs that go to lake Michigan. Don't be a pussy, do the dune hike.
On the way to SSM you should stop to see Mackinaw city. It's a bit schlocky like Wasaga beach but your kids would probably like it.
The UP (upper peninsula) is like northern Ontario. Not very populated but absolutely beautiful especially if head to the north shores of Lake Superior.
If you have any questions, hit me up.
