A limited season sale next spring drops the price for Seattle to Zurich down to $412-$420 round trip on Icelandair and Star Alliance carriers drop fares to $418-$456 for April-May departures. I found $418 United tickets on Momondo.com. Departure dates are only from around April 3 to May 10 at these $400s prices.
Air Canada, Swiss, Lufthansa, United and Icelandair all have low round trip fares in $400s.
At these prices, you can pick up a flight to Seattle from many western states cities for a good deal to Switzerland.
United Airlines Seattle – Washington IAD (UA) – Zurich ZRH (UA) – San Francisco SFO (LX) – Seattle SEA (UA)
Momondo.com meta-search April 21 – April 28
- Icelandair $412 round trip
- United $418 round trip