The flight time between LAX and SAN is 16 minutes in an AA RJ. I actually prefer the old prop planes as its a very scenic ride up/down the coast that you don't get to enjoy nearly as much with the jet. The biggest problem is that BA will book you with an extra long connection time in LAX. After going through I&C at TBIT, if you drop your bags at the bag drop and walk over to AA, you are locked in to your original flight, sometimes for a 2 hour wait. The key is to take you luggage with you when you leave TBIT so that you can catch an earlier flight. It's not ideal.