This deal from last month is still available. Dates have changed from August-December to September-November. Expect fluctuations like this as the deal ages.
American Airlines has round-trip flights from Chicago (ORD) to Miami, San Francisco, Phoenix, Fort Myers, Los Angeles, Dallas, or Knoxville (MIA, SFO, PHX, RSW, LAX, DFW, TYS) for $121-$148, NONSTOP. Flights September to November. Mostly Tuesdays, Wednesdays, or Saturdays. Extended weekends available. Origin/Destination reversible. No Christmas dates available.
A Carry-on bag and also a personal item is allowed for free on American. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.
Click for more details and booking links Nonstop Flights: Chicago to/from Miami, San Francisco, Phoenix, Fort Myers, Los Angeles, Dallas, or Knoxville $121-$148 r/t [September-November] (Tue, Wed, Sat) – American Airlines / United