Right now there’s the lowest fare available that I’ve seen between the West Coast and Europe in awhile. You can fly San Francisco to London for as little as $263 roundtrip. And it’s not even a basic economy fare, it’s on Icelandair which gives you an advance seat assignment, a carry on bag at no extra charge.
But that’s not all, fares between the US and Europe are available from a variety of cities and on several airlines, each with a Google Flights link that’ll pull up a sample itinerary at the current lowest fare: