Originally Posted by Lanesplitter

Milwaukee, though interesting and cool in it's own right, I only suggested because I think it's a great place to begin a bike tour. The reason is, between Chicago and Milwaukee there's a fair amount of congestion. While there is a significant rail trail which helps a ton, there are also large segments without. Once you get out of Milwaukee going north, however, there's a long rail trail, then, before you know, you're firmly in northern Wisconsin, which has no traffic at all. Wisconsin is very quiet once you get up north. There is also a very extensive network of rail trails. I went out there for a second time last summer and really loved how serene it was. It seemed like every park we had to ourselves. It's not like that everywhere. Plus people drive very calm. No horns or close passes. Ever. It is a lot different, even across the lake, in Michigan, to say nothing of the northeast.

One could even head west at Green Bay to Minneapolis, Minnesota, then back to Chicago by train as another very quiet option. Minnesota has tons of rail trails, including the Paul Bunyan trail, which is the longest paved one in the country. Deep forests and lakes, plus pancake flat. Maybe the flattest area in the country one can tour while still enjoying epic scenery.

Anyway, I hope you have a great tour! There are tons of great suggestions here. Cheers!