4) The Avis/Budget office is straight ahead, through the parking structure and out to the standalone

I've found the best rental prices (saving as much as 60%) using Avis and Budget in San Bruno. They share an office in the back of the Sears Auto Center building at the Tanforan Shopping Center which is adjacent to the San Bruno BART station. San Bruno is one stop before SFO. After you exit BART, you have to walk through the upper parking lot, the upper level of Target, through the shopping center, through Sears, and out to the Sears Auto Center.
factory tours california Are you from the States? If so, I don't think Holiday Autos will be an option. They have good deals and one way rentals . . . to visitors from overseas. AFAIK their offers aren't available to US residents (though do check them out - things factory tours california may have changed)
4) The Avis/Budget office is straight ahead, through the parking structure factory tours california and out to the standalone Sears Auto Center. The office has an awning with the Avis and Budget names and is located factory tours california next to the auto center's garage bays.
If you have an American Express card, this might work for you. I was having no luck getting a good deal on a car at Dallas-Fort Worth Airport. Then, today, I got a pop-up on the American Express site suggesting I go to Dollar Rent A Car and use the promo code AXFLY. I did, and I am extremely pleased with the result--$150 less than I found anyplace else.
If you are going to San Bruno from San Francisco, take either factory tours california the SFO or Millbrae BART train. San Bruno is one stop before SFO and one stop before Millbrae (Millbrae trains bypass the airport on weekdays before 6pm). The fare from a downtown BART station is $3.95. It's about a 30-miniute ride.