For SFO, you can always go via LAX; frequent connecting AA service, very fine lounges in LAX while you wait, BA A380 from LAX if you want either side bins or the best F seat (depending on class).[/QUOTE]
This is a good tip, which I have done several times and reward availability seems to be better to LAX. I try and avoid OAK because of the LGW/777 combination.
I'm also partial to use Southwest to connect as they have so many flights up to the Bay Area, coupled with the ability to change a ticket at no cost up to 10 minutes before a flight and a free bag. They do exactly what it says on the tin, usually with a smile and decent humour.