Several cities are available for $98 on DL from ORD -- at least PHX, LAX, LAS, SFO and SEA. Fly Tuesday, Wednesday or Saturday. Fly other days for $20 more each day. Looks like you can change in any hub you want, but for mileage run purposes you'd want to do something lke ORD-ATL-SEA-ATL-ORD.

With taxes I'm getting fares of around $112.