If you don't mind reserving now and traveling to Europe in November, Icelandair is offering bargain fares from Sea-Tac to Europe for less than $550 roundtrip.
The airline flies from Sea-Tac to its hub in Reykjavik, Iceland, where passengers can switch to flights to other European destinations. The airline, which has flown from Sea-Tac for a year now, is offering $549 fares to Oslo, Stockholm, Copenhagen, Frankfurt, Paris, Amsterdam and Glasgow. If you’re going only as far as Reykjavik, the fare is $365. All fares are exclusive of taxes and fees.
Seats are limited, and they must be reserved by Friday.