It's an easy, nice route. As soon as you enter UP Michigan stop at a Chamber of Commerce or Visitor Center and ask for the waterfall map. Some nice ones in the western UP with easy walks.
Copper Harbor is a neat area as are Munising for Pixctured Rocks Nat'l Lakeshore, Paradise for Whitefish Point and Sault Ste Marie to watch the big ships.
I'm sure you know you have to take a ferry to Mackinac Island. No cars allowed. Stay in St. Ignace or Mackinaw City.
If continuing onward be sure to explore Leelanau Peninsula/Traverse City and Sleeping Bear Dunes Nat'l Lakeshore - we've volunteered there ..... beautiful countryside. Drive from Mackinaw down the lakeshore on 31 and explore Petoskey and Charlevoix. If running, do the day trip ferry to South Manitou Island. We gave the lighthouse tours there.
That whole area holds a special place in our hearts!