Check out
www.airnav.com and see what DuPage or Aurora or Joliet have to offer. Or just type "Chicago" in the airport section of airnav and that should come up with a list of all the airports in the Chicago area. If you have the time and the transport, Poplar Grove is an airpark on the outskirts of Chicago which is well worth a visit just for plane watching. They also have a museum there.