80 from Des Moines to QC isn't bad. I'd look into taking 80 to 61 then go North through Dubuque which then turns into 151 which is a great road but hilly at times (no tolls). That will take you to Madison where you can hop on the belt line East and catch 94 to Milwaukee.
Illinois roads pretty much stink but the 88 to 39 to 90 to 43 might be another option (toll in Dixon though).
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Jack of all trades - Master of none
2012 F350 CC DRW - 6.7L PSD
2014 Sabre 36QBOK
Oh, and if you want to stay in QC area overnight, Scott County Park is excellent. It is off of 61. If you take 88 there is a place called Sunset Lakes Resort by Joslin. Great place, but it is a little pricier (kind of like a Yogi Bear campground). Great group of people that run it.
__________________
Jack of all trades - Master of none
2012 F350 CC DRW - 6.7L PSD
2014 Sabre 36QBOK
Another option would be 80 to the QC area. Then 88 to 39 north. Once you cross the IL/WI state line take 43 to Milwaukee. We take this way from Davenport to WI when visiting my mother and sister & BIL. Yes there are a few tolls on 88 and one north of Rockford on 39 but the roads and pretty flat. Just an FYI, the beltline around Madison WI can be a slow go if you travel it during the wrong time of day (rush hour).