I did a tour in 2006 from Baltimore to Rock Island, Illinois, that went through D.C. and Kankakee, so passed near Chicago. An objective of the tour was to include as many trails as practical. From D.C. I rode the C&O Canal Trail and GAP Trail to Pittsburgh, the Montour and Panhandle Trails south and west of Pittsburgh to Stubenville, Ohio, on the Illinois-Ohio border, then across Ohio (through New Philadelphia, Mt. Vernon, Marion, and Lima) and Indiana (through Blufton, Logansport, and Rensselaer) to Illinois. Other than a half day of climbing on the south end of the GAP Trail and two days of stiff hills in eastern Ohio, the route involved almost no hills and was on trails or country roads. Rode the I&M Canal and Hennepin Canal trails across most of Illinois to Rock Island.
I can send you the itinerary and journal of the tour if you're interested.