I have some stuff I have to get done, but I'll get back to you. Are you sure you don't want to spend some time in the Milwaukee area or head northeast up to Door County?
Quickly off the top of my head there's the Dells- waterparks galore, they also have the Tommy Bartlett waterski show and some "museum" type thing, the ducks (amphibious vehicles) that go down the river and it's quite pretty with the cliffs, there's also Circus World Museum in Baraboo (supposedly the Circus got some of it's roots here, who knows).
There's a bike trail that the name escapes me at the moment. Up in Chippewa Falls there's the Lennie's brewery. Along with the rest that people mentioned above.
When this summer are you going? There are random festivals and events.
If you want to reconsider throwing in some time in Milwaukee or Door County I'd highly recommend it. Milwaukee has the Imax, Public Museum, and Discovery World Museum (good for kids and still fun for adults), and Pier Wisconsin too. The Milwaukee Art Museum with the awesome Santiago Calatrava addition, the lakefront, numerous festivals (basically every weekend they start end May and continue through September including Jazz in the Park in Cathedral Square (Free) every Thursday, River Rhythms in Piere Marquette Park every Wednesday (free) and River Flicks in the same park some random friday nights throughout the summer (free), along with random art shows and neighborhood festivals and farmer's markets.
Door County is gorgeous with State Parks, cute B&Bs, golf resorts, art gallerys, fish boils, boating, cute boutiques, hiking, etc.
As boring as WI may seem to people there's heaps to do (year round), but especially in the summer May-September/October.
I'll get back to you about things to do in the western part of the state (it's hillier there and it is pretty), but if you have time I'd consider some things in the Southeastern area.
So how much time will you have and what part of summer?
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