United has round-trip flights from Austin (AUS) to San Francisco (SFO) for $119, NONSTOP. Flights March to May. Departures on Tuesday, Wednesday, and Saturday. Extended weekends available. Origin/Destination reversible.
Change fees are waived, but United’s “Basic Economy” fares do not include a free carry-on bag. Only a personal item (like a small laptop bag) is free. Seats are randomly assigned for free prior to boarding. If you have the United MileagePlus credit-card, use the “free checked bag” perk.
The personal item size on United is smaller (9-in/10-in/17-in) than Frontier or Spirit (8-in/14-in/18-in).
Click for more details and booking links Nonstop Flights: Austin to/from San Francisco $119 r/t [March-May] – United