Mark:
Several thoughts:
-- The Sheboygan-Kohler-area courses (Blackwolf Run's River and Meadow Valleys courses, as well as Whistling Straits and the next-door Irish Course) are the state's premeir destination courses. Combined with accomodations at the American Club, this is certainly the top-of-the-line that you can get in Wisconsin. Details here:
http://www.destinationkohler.com/ Not inexpensive by any means, but certainly the best public golf and accomodations in the state. Caveat: Something of a detour on the way from Chicago to Minneapolis; Sheboygan is an hour north of Milwaukee in good traffic, and then it's another two hours from Sheboygan back to the interstate that takes you to Minneapolis.
-- A somewhat lesser detour is Lawsonia, much trumpeted on GCA threads. About an hour detour one-way from the interstate to Minneapolis. Near the resort-ish town of Green Lake, an idyllic part of central Wisconsin. Details here:
http://lawsonia.com/lawsonia/index.htm You can stay on the grounds at Lawsonia (no booze, natch...) or opt for something like the Heidel House, a very nice choice in Green Lake:
http://www.heidelhouse.com/ An old Bendelow course, Tuscambia, which dates to pre-1900, is right next door to the Heidel House; something of a museum piece of a course. The Links course at Lawsonia is the much-preferred course; worth playing twice before any of the others.
-- A similar detour in length would be Erin Hills, northwest of the Milwaukee area. Much anticipated in these parts, said to be a candidate for the US Open, with wide variety of opinions from regular GCA posters. Details here:
http://www.erinhills.com/-- In the schlocky Wisconsin Dells area, right off the interstate about an hour north of Madison, sits Trappers Turn, a very nice course designed by Wisconsin's Andy North, a two-time US Open champion. A nice stroll, some good scenery, some challenge without being over the top. Details here:
http://trappersturn.com/ A new course open this year in the Wisconsin Dells area is Wild Rock, which is getting some good initial reviews and is much anticipated because it's done by the same folks (sans Whitten) who did Erin Hills. See here:
http://www.wildrockgolf.com/-- In Eau Claire, about two hours east of Minneapolis, sits Wild Ridge. Details here:
http://www.wildridgegolf.com/ I have not played, but it's gotten good reviews from folks on the GCA board and elsewhere.
-- Also in Eau Claire is Eau Claire CC, which I believe is private but probably open to an inquiry. Subject of a fairly famous GCA thread by frequent poster John Conley, who absolutely raves about it. See this:
http://golfclubatlas.com/forum/index.php/topic,3001.0.html I'm guessing an IM to John might help with access questions. A good club website with fairly extensive details on the course:
http://www.ecgcc.com/-- Pro golfer Tom Lehman built Troy Burne on land near the bluffs of the St. Croix River that separates Wisconsin and Minnesota. A 10-minute detour off the interstate, and about an hour from downtown Minneapolis. Details here:
http://www.troyburne.com/view.asp?id=396&page=10683 I have not played; it's gotten pretty good reviews from folks in Wisconsin.
-- Just north and a bit east of Hudson is New Richmond Golf Club, with 27 holes. A low-key course that nonetheless is often used by the Wisconsin Golf Association for tournaments. Details here:
http://www.nrgolfclub.com/The GCA board has plenty of Chicago and Minneapolis-area posters who are better in those states than me. This is a decent run-down of what's available in Wisconsin relatively near the direct route from Chicago to Minneapolis. Feel free to email/IM if you need more help with anything Wisconsin-related for their visit; be happy to help.