Vacation...

It's a beautiful day here in Wisconsin. Summer is a short season, usually, for us, so we have to enjoy every warm day we get. The last few days it was in the high 90's and very humid. Not nice! :)  Today; 80s and a lot dryer.
Today is my last day of work and then I have a week off. Still not sure what we're going to do on this vacation and am looking for suggestions. We've been thinking about visiting the Cave of the Mounds with our 3 grandchildren. Haven't been there since I was very young. I enjoyed it then so I'm hoping our grandkids will to. Does anyone have any other suggestions of " day trips" we can take next week?