Dear Steemians,
©TripAdvisor.com
With KLM you can fly for 514 Euro from Zürich to San Francisco.
Flights are available from April until December.
You can book here
http://m.momondo.de/results?cur=EUR&o=ZRH&d=SFO&dd=2018-04-11&rd=2018-04-18&a=1&ti=ECO&stops=any
Have fun