if your going to drive through madison to IL, thats adding time. its really pointless. we all could meet up in iowa really.
FYI as i just did the drive as in 48 hours ago, from Milwaukee WI, its about 3 1/2 hours to cedar rapids or 4 hours to iowa city. takes roughly 1 hour 15 - 20 minutes to madison. there is almost no traffic until you hit the Madison circle but that's about it. its not even that bad as you avoid downtown all together and got off towards dodgeville anyway. then its empty most of the way.
this is going to madison, through Dodgeville and Debuque, and finally to Iowa city. and no tolls
. so it should take roughly 2 1/2 hours to get from madison to iowa city, thus making the trip from madsion a quick drive for the most part.
i say a meet and greet for an hour in iowa city or something of the sort and then get back on the road