The Sheriff has snowmobile patrol scheduled through the 1st week in June this year up near Grand Marais and Tahquamenon
Good advice from Diver Dan. On the way up, hug the coast. Crystal Lake, Sleeping Bear Dunes, Glen Arbor, Leland. The Leelanau Peninsula is loaded with wineries. Then down to Traverse City. If you're a Hagerty fan, they are HQ'd there and usually have stuff on display. They had the Lunar Lander there last summer. Then continue up thru Torch Lake, Charlevoix, Petoskey, Harbor Springs, etc. If you're into beer, stop at Beard's Brewery in downtown Petoskey. Owned by Ben Slocum - rally co-driver extraordinaire of $500 BMW Rally Mexico fame. Also did the Dakar. He's got stories
If you're into downhill skiing, stop at Shaggy's in Boyne City. Tiny custom ski maker and they will give you a highly personalized tour. If you're into music, go to Interlochen - sort of a music mecca south of Traverse City.
Also, in St. Ignace (just over "The Bridge") try Timmy Lee's on US2. Doesn't look like much, but some of the best lake fish anywhere!
Closer to SW Mich, go to Founder's Brewery in downtown Grand Rapids for lunch/dinner. Also, the Gilmore Car Museum near Kalamazoo is spectacular and unlike any other car museum I know of.
Weather 1st week of May: it will be somewhere between 25 and snow & 75 and sun.
And keep expectations low on Sault St. Marie (US or Canada sides). There's not much there!