Alaska Airlines has round-trip flights from Dallas (DFW) to Portland, Oregon or Seattle (PDX, SEA) for $111-$147, NONSTOP. Flights August to November. Very few weekends available. Origin/Destination reversible. No Thanksgiving dates.
A Carry-on bag and also a personal item is allowed for free on Alaska Airlines. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.