An interesting addition to the one-way fares posted for San Francisco to London Gatwick is TAP Portugal $302 one-way for travel departures into March 2017. WOW Air flies SFO to London with one way ticket prices and Norwegian flies Oakland to London LGW with one way ticket prices, however, both of those airlines have high bag and seat assignment fees. TAP Portugal does not fly from SFO. A partnership with JetBlue connects passengers between San Francisco and New York JFK or Boston.
TAP Portugal round trip ticket price SFO-London LGW is around $683, but there are similar fares to that with American and Delta/SkyTeam for travel during this same period.
What I find attractive about the TAP Portugal fare is not the Star Alliance miles aspect, since this is a low to no miles economy booking code, but rather the option to get a one-way ticket to London for $300 all-in with all day in Lisbon and international lounge privileges for Star Alliance eligible elites.
A one-way TAP ticket provides the option of booking a return trip from London/Europe to San Francisco for about $400 round trip from places several cities in Europe.
TAP Portugal San Francisco SFO (JetBlue) – New York JFK (TAP) – Lisbon (TAP) London Gatwick LGW