ActiveCaptain.com is a great free user input resource, which gives you charts online and reviews of marinas and anchorages.
Skipper Bob's Publication, "Cruising from Chicago to Mobile", is also very a very valuable mile by mile guide covering marinas and anchorages.
I would suggest the Waterway Guide for the Great Lakes to cover Lake Michigan.
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While the Illinois River may not be the greatest cruising around, it is beautiful in its own way. We went from Chicago to Mobile last year and found many interesting small towns and an incredible amount of history. You are in peaceful river settings, surrounded by nature and treated to great sunrises and sunsets.
You could get a feel for it by reading our blog starting in September, 2012 from Day 2 where we arrived in Chicago to Day 13 where we joined the Mississippi. There are links to these days on the archive at the right.
Adventures of Great Laker