Delta, Virgin Atlantic, Air Europa, Air France and various other airlines have round-trip flights from Seattle (SEA) to Madrid (MAD) for $431-$444 with a connection. Flights February, March, October, and November. Departures on Monday, Tuesday, Wednesday, and Sunday. No Thanksgiving 2023 dates.
A Carry-on bag and also a personal item is allowed for free. You can avoid paying for seat selection by accepting the randomly assigned seat at the gate.