American Airlines has round-trip flights from Dallas (DFW) to St. Louis, Seattle, or Indianapolis (STL, SEA, IND) for $131, NONSTOP. Extended weekends available. No Christmas dates available.
St. Louis flights: in December, February, and March. Departures on Monday, Tuesday, Wednesday, Thursday, and Saturday.
Seattle flights: January to February. Departures on Monday, Tuesday, Wednesday, Thursday, and Saturday.
Indianapolis flights: in December. Limited availability.
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.