BA was flying to San Diego from LHR pre Covid. I can't keep up with what is still on the books. I'm assuming you checked and that flight is cancelled now.
You don't need first class from SF to anywhere on the west coast if you don't mind sitting in the back for an hour or so. The flights (did) run multiple times a day from the airports in the Bay Area (SFO, OAK) to both Las Vegas and San Diego and are very reasonable. We'd usually take Southwest because the price point is usually terrific. Southwest is a good choice for the west coast and PDX. I did just take Frontier from SAN to LAS for $39 r/t. No luggage allowance for that fare, but it was just a quick 2 day flight.
That said, I'm going to move your question to the USA forum for further discussion.