Chicago is great because of the variety. You have the touring shows downtown in the big barns. You have the big-time resident theatres like the Goodman and Steppenwolf and Chicago Shakespeare and the Cort. You have mid-size rental houses where bigger-but-not-huge shows can play like the Royal George, The Mercury, Victory Gardens, and the Athenaeum.
But beyond that the non-eq scene is great, and smaller companies that play in storefront spaces and small venues like the Theatre Building or City Lit do really great work for very cheap tickets (though the actors don't get paid much, but they're doing it for the love.) Plus you have the improv scene and Second City, the original "Too Much Light Makes The Baby Go Blind" and those sorts of oddities, and it all adds up to a very broad scene.
The one thing I feel that Chicago doesn't have much of is good new musical theatre. For all the great work that gets done there, I can't think of a single musical since "Grease" that originated in Chicago (not counting an out-of-town tryout) and went on to be a big hit.
The Chicago Reader has a great comprehensive listing of what's playing. You can check out what's on right now at the link below:
Chicago Reader Theater Listings
