Another competitive option from Germany (Dusseldorf or Berlin) to California these days this time based on British Airways, UK flag carrier and member of Oneworld alliance. Round-trip flights to Los Angeles are now available already for €299 and to San Francisco from €365 in winter season 2017/2018 . Flights have one short layover in London on your way. Remember you can not skip first leg of your outbound flight between Germany and UK. Rest of your itinerary would be cancelled..Moreover you can also book an open jaw tickets which is great option to travel Califronia without need of returning back to city of arrival.
British Airways promotion is available for flights between November 2017 and April 2018. Blackout period around Christmas holidays. Max stay 3 months. Discount applies to bookings made till 15th of July 2017 or till the cheapest tariff is sold out..Below you can find our booking sample.
Booking sample
Dussledorf / Berlin - Los Angeles from €332 (Directly with BA also compare your travel options there)
Open-jaw solution
To book your accommodation in California in advance you may use Booking.com. You can also use Amoma or Hotels.com promo code.
Booking sample of latest promotional sale of British Airways cheap flights from Dusseldorf to California from €299 here. In this case you will be departing from Germany to Los Angeles on 28th of January. You would be returning from USA to Europe on 10th of February 2018.