Michigan’s Upper Peninsula

Wilderness State Park and Mackinac Island.
From an ex-Michigander

Don't forget about Pictured Rocks National Park and National Lakeshore, which is very beautiful. You can hike there and climb down to see the pictured cliffs up close. It's a lovely place to visit.

I would also suggest visiting https://www.uptravel.com, which lists so many places you can see in the UP, and places to stay. The last time I drove there, I stayed in Marquette, which is a very small city but the largest city in the UP. There are a number of lodges and hotels there, and it's a convenient location. But if you're looking for more out-of-the-way places, there are many other towns to choose from. The link I post above (uptravel) has a trip builder that can use to plot places you would like to see. https://www.uptravel.com/plan-your-trip/

ETA: When you're on Isle Royale, you're actually pretty close to Grand Portage State Park in Minnesota, which has a gorgeous waterfall that is located only about a half mile from the entrance. I believe there is ferry service between the two places.

I second Pictured Rocks Nat'l Seashore. I love the drive up the Keweenaw Peninsula to Copper Harbor. Definitely Mackinac Island. Tahquamenon Falls SP is beautiful. I've stayed in Escanaba, Marquette, Munising, Copper Harbor, and Manistique - on several different visits. It's a beautiful area of the country. I'm a lighthouse lover and there's no shortage of those in the UP. Be sure and try a pasty when you're there.

I've spent almost 6 decades of my life in the metro Detroit area. Our favorite getaway is to take our bikes to Mackinac Island - no cars! Pictured Rocks is also a favorite as is Tahquamenon Falls State Park which is MI's 2nd largest state park. Get a pasty in St. Ignace!

Echoing everyone else here - Mackinac Island, Tahqaumenon Falls, Pictured Rocks. Might check out Ste Saint Marie for the locks, etc. Houghton is cute and a good base for exploring the Keweenaw Peninsula. If you have time to travel further south, Traverse City is well-worth a visit for hiking, wineries, great restaurants, etc.

Get some pasties somewhere - https://thepastyguy.com/portfolio/the-pasty-trail-best-pasties-in-up/

Porcupine Mountains State Park and Lake of the Clouds overlook.

Ditto. Great wilderness hiking.

Another option would be to visit Isle Royale from Minnesota. It's a shorter journey on the water, and the entire North Shore is a beautiful place to vacation. There are eight state parks with an abundance of waterfalls and hiking trails with spectacular views of Lake Superior. Duluth, Two Harbors, Grand Marais and Ely (inland on the edge of the BWCA) are all fun towns. Here's a mile-by-mile guide of the North Shore.

Door County in Wisconsin is one more place to look at for your extra time. There are five state parks to explore and lots of activities everywhere.

This is a great Isle Royale book.

Enjoy your trip!

This is breaking news happening near Isle Royale this morning.

Also, another destination on Lake Superior is Madeline Island in northern Wisconsin.

Another vote for Pictured Rocks. You can drive to Munising, to the docks, and take a small cruise boat that follows the shoreline and gives you great views. The whole shoreline between Munising and Grand Marais (the MI one), is full of parks and hiking trails.

You can drive through Hell, Michigan, and Christmas, Michigan, and then say you did.

I love pasties (paaasties, not paste-ties), WITH gravy (a sacrilige to many Yoopers).

Oh yeah, da Yoopers Tourist Trap, on US41 in Ishpeming, MI. Link