Thoughts
Congratulations on your decision. With the exception of your new stadium, I have made the complete circuit twice and it is really fantastic.
Find a used book store on-line (abebooks.com or something like it) and find Bob Wood's book "Big Ten Country" from 1989. While obviously dated in many respects, it still is a great read of his journey to all the 10 places in the league (before Penn State came in) and his explorations of the unique traditions at each school as well the cities where they are located.
http://www.thebig10tour.com/ This is a blog of the circuit that was made a year or two ago. From a much younger perspective than Wood's book, but still some interesting things to read.
Some suggestions on your destinations.
MSU has some very precise regulations on tailgating that depend on the time of the game in terms of what times that parking lots open on campus. Keep that in mind. You also might consider staying in either Kalamazoo or Jackson and finishing the drive on Saturday morning to avoid the add on charges for hotels in Lansing on a football Saturday. The main drag is the north edge of campus and it is very charged with energy on Friday nights as well as before and after the game. There must be some requirement that all MSU students must be carrying a case of "Natural Light" on game day mornings from the local liquor mart. MSU is one of the prettier campuses in the conference in both buildings and coeds, so I would highly recommend taking some time to explore.
In going to Champaign, I would highly recommend getting to the stadium early and walking around. Memorial Stadium is a World War I memorial and, in my opinion, one of the better designs of the bunch. Each column is inscribed in the memory of an Illinois student who lost their lives in service to the United States during the war. The place is full of history . Around Memorial Stadium are some nicer old barns and such if you are into that kind of thing. There is lots of space for tailgating so plan to make a day of it. I don't know much about Champaign nightlife, since it is an easy day-trip for me to make.
As far as Purdue, make sure you fit in a trip to the Triple XXX. Fabulous food in a building that is pretty much frozen in time. I would highly recommend that you avoid Chicago on the drive (as others have suggested) and come via I-74 (past Champaign) and then either drive to Indianapolis and then go up I-65, or take back roads for the last hour of the trip so you don't dip so far south. Purdue is fairly far removed from the Interstate, so plan for a nice tailgate afterwards to let the others fight the traffic.