I found some pretty comprehensive lists of rides that are maintained by some people in our area. Reposting then here as they are a great resource for finding some midwest events.
Midwest rides:
http://www.mikebentley.com/bike/mwrides.htm
and
http://highergearchicago.com/training_riding_racing/chicagoland-cycling-calendar/
Illinois specific ones here as well:
http://www.mikebentley.com/bike/ilrides.htm
all sorts of other intereting links here:
http://www.mikebentley.com/bike/
enjoy!