United Airlines offers roundtrip flights to California from select cities in the U.S. with prices starting at $138, as provided by ShermansTravel. (Click on "United.com" in the main paragraph to see this sale; all taxes are included.) That's the lowest current rate we could find for select routes by $12. This price is valid on flights departing from Portland, OR, (PDX) to San Francisco, CA, (SFO) on May 27; prices vary depending on the departure cities and dates chosen. Blackout dates may apply. Book this travel deal by April 25 for travel May 1 through June 30. Other notable routes: