Try the area around Rosemont/O'Hare - $100 per night might be tough to attain, but perhaps by danlging the possibility of a lot of business in front of the hotel/motel, you might be able to get a better rate than normal. Most all the major chains have hotels in and around O'Hare. The other advantage of this area is that not everyone would have to drive to Chicago or rent a car, as the "L"/buses serve Rosemont ("L" station is at River Road/I-190) and the chains usually have courtesy vans that can do pick-ups/drop-offs from the airport or to other area locations.
There are a lot of restaurants around the hotels near the "L", as well as over by the Allstate Arena (essentially, Mannheim & Touhy) - Steak-n-Shake, etc.
Another possibility would be out along I-88 in the Naperville area. The Prototype Model RRs group has met at a Holiday Inn out there for several years running now. However, Naperville's not particularly close to O'Hare or Midway. It has Metra-BNSF access, but that is somewhat remote from where the Holiday Inn is located.
Hope this helps!