Philippine Airlines, United, and Singapore Airlines have round-trip flights from Seattle (SEA) to Singapore (SIN) for $773-$808 Nonstop, or with a connection. Flights January, February, March, April, May, August, September, and October. Departures on Monday, Tuesday, Wednesday, Thursday, and Sunday. No Fridays or Saturdays. Extended weekends available.
Some small OTAs on Skyscanner and Google have this for cheaper than the airline. If you plan on booking there, beware of any site that charges a fee to cancel a ticket within the 24-hour “free” period. Use unknown booking sites at your own risk.
Singapore Airlines fares are NONSTOP, you should prioritize those above the other fares, even if the price is slightly higher.
Click for more details and booking links Cheap Flights: Seattle to Singapore $773-$808 r/t [Jan-May, Aug-Oct] – Philippine Airlines / United / Singapore Airlines / Skyscanner