A good number of Midwest cities (OMA, DSM, MCI) see 757 service, especially from DEN. The loads and yields warrant it (apparently?), and these cities are good locations for aircraft to RON before a busy day of flying. The aircraft typically operated late-evening flights to these cities, sit overnight, and then operate short morning hops to DEN and ORD. Sometimes they operate "through" flights through these cities to propogate aircraft to and from ORD and DEN. It's more rare to see a mid-day 757 turn in one of these cities.