We've a great experience in Chris & Tim's house.
We stayed as a couple in their house for one whole week and they were the best guests we could ever imagine. Everyday we had a hot coffee and fresh fruits on the table as well as home-made bread with butter. They were very attentious as we arrived right in the morning and they made us feel as home. I just didn't realized how the week was spent so fast that I wanted to stay longer when the day of leaving had arrived. Clean, comfortable, in a very nice neighbourhood, we could get from there to anywhere in town in few minutes and walking only few blocks to take the bus. Lines 8X, 9, 9L, 24 and 44 are of great help to get to Presidio, The Golden Gate Park and the Golden Gate itself, downtown SFO, Alcatraz, Union Square, Civic Center, Castro... I mean, it's perfect.
In order to get there from the airport, one can take the shared vans (17 dollars each), a taxi (it's going to be even cheaper!) or a Bus (the 292 line - it costs 4 dollars), which has an stop over the August St, which is very close to their place.

I'm coming back to SFO in the end of the year and surely I'm going to be on their place!