You could spend a while touring all the breweries in Wisconsin. Here's a short list with locations. (Add if I missed any!)
Ale Asylum, Madison
Leinenkuegel's, Chippewa Falls
New Glarus, New Glarus
Sand Creek, Black River Falls
Grumpy Troll, Mt. Horeb
Capitol Brewery, Middleton
Great Dane, Fitchburg
Point, Steven's Point
NorthWood's, Eau Claire
I've been to these and I'm sure there are more out there. Wisconsin is one of the best for a good brew!
It depends on where you are going in WI, we have a ton of really interesting stuff to do.
In Milwaukee, there are great museums, restaurants and festivals, especially in summer time. Spend a lot of time in the third ward and the lakefront.
If you're going up north, stop in Oshkosh to check out the Paine Art Center, the Grand Opera House, the EAA museum and they just made major improvements on main street, it looks great. On the other side of Lake Winnebago, High Cliff State Park is beautiful throughout the year. Just a bit north of that is Appleton, college avenue has a ton of stuff going on. (Check out Muncheez pizza, the best pizza in town IMHO.)
I don't spend a lot of time out west or in Madison, but if you're going to visit our state capital, take a tour of Capital Brewing, and definitely walk around or use buses in the city, I know people that have lived there forever and they still can't get around!