Jetblue Airways have round trip airfares travelling to and from Boston (BOS) and Seattle (SEA) for $197, nonstop.
Travel Availability:
Departs BOS: Feb 7-12, 19-20, 25-28
Departs SEA: Feb 7-8, 11-13, 19-20, 25-28
Use dates and book it on your reputable and known OTAs such as Expedia , Orbitz , Priceline or Jetblue Airways.
http://www.expedia.com/