Andy Crouch of BeerScribe knows a lot about beer. Promise.
In his post Six Beers for Autumn, he talks about two styles, the Weizenbock and Marzen, as under-appreciated classics fit for fall consumption. I agree completely (and will post more in the coming weeks about other fall classics). Some of his selections are available in various parts of the Midwest, but I thought I'd offer some other examples made closer to home. Check out his post for great descriptions of each style and why they're so fit for fall (as an aside, Marzen is the name for the classic Oktoberfest beer).
Great Lakes Glockenspiel
Capital Brewery Weizen Doppelbock
Great Lakes Oktoberfest
Three Floyds Munsterfest
I also encourage you to check out your local brewery and brewpub, be that in Chicago or elsewhere, for any new seasonal offerings. And let me know too, so I can share with everyone.