American Airlines and Oneworld carriers have round-trip flights from Seattle (SEA) to Amsterdam or Paris (AMS, CDG) for $423-$488 with a connection. Flights in August, October, November, December, January, February, and March. Departures on Monday, Tuesday, Wednesday, and Sunday. 7-day minimum stay required. Holiday blackouts.
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.