After a few trips up to Wisconsin, I'd have to say that my favorite place so far is Jerry's Old Town Inn in Germantown.
They had great ribs, wonderful service and you have to try the French Onion Soup! It is the best I've ever had...*drool*
I was there on Thursday, but from what I hear, their traditional Friday night fish fry is excellent as well. It's on the way to the rally, and would be an excellent place to have a reservation!
The Riverside Brewery that Sue mentioned had excellent food as well!