House on the Rock in Wisconsin. It’s pretty cool.

Pictured Rocks National Lakeshore

Anywhere along the shores of Lake Superior is nice, lots of good hiking

Driftless area: NE Iowa, SE Minnesota and SW Wisconsin

A few off the top of my head:

If you like theme parks and especially if you have kids, Holiday World in Santa Claus, Indiana is one of the best.

If you like hiking and the outdoors, Garden of the Gods in Illinois.

If you’re into military history and/or stuff that flies, the National Museum of the US Air Force in Dayton, Ohio.