Briefly, this was my preferred route when heading NW. If you check the maps, it makes more sense than the text below.
(I always avoided the Indiana Toll Road by using US-20)
Exit Ohio Turnpike at Western end
Take US-20 West almost all the way across IN
Exit onto State Road 2 (SW of South Bend, IN)
West on State Road 2
State Road 2 joins US-20
West on US-20
Stay on US-20 until it crosses I-94 in MI
Take I-94 West into IL
I-94 and I-80 join
Stay on I-80 West
Stay on I-80 West BUT to do so,
*** you have to exit for a toll booth soon after you cross the S.Halsted Rd. interchange.
*** After the toll booth, the road swings to the left and rejoins I-80.
*** (Note: That will be your ONLY toll since leaving the Ohio Toll Road.)
Stay on I-80 West
Take I-380 North just West of Iowa City
Then US-20, US-218, and US-18 until it crosses I-35
Take I-35 North to I-90
Fuel was cheaper in IA so I always fueled at the Flying-J in Davenport, just off I-80.
Virtually all of the non-interstate roads along this route were very good with little traffic. In many places, they are 4-lane roads.
Like others have said, hit the Chicago area at non-rush hour times... and
be sure to adjust for time zones changes!