Hubertus House of Horror is always good. Best bang for your money: The Dark Side Haunted Adventure in Ixonia--well worth the drive! You get a haunted house, hayride, walk through the woods and corn maze all for the price of one. Only haunted adventure that I have been truly terrified of!
There are tons of places you can go! There's the Wisconsin Feargrounds (wisconsinfeargrounds.com), Mars Haunted House, Hauntfest at State Fair, The Hill Has Eyes in Franklin, the list goes on and on. Mandy Runnalls mentioned some good ones as well! Some helpful sites to aid in your search: