We stayed five nights during our visit in SF at Melissa's place. She and her family are wonderful hosts, caring about the well being of her guests, assisting where needed. The place is cosy and clean, has a great shower, good coffee and tea and is very quiet. But it is still very close to the city. About five minutes walk to everything you need including restaurants, muni transport and washing locations. It took us about 20 minutes to the very centre (union square) by train or bus, which seem to go all night (at least till 11pm).
It is a bit small so if you expect a big flat, you won't get it. But there is a desk, some cupboards with a fridge and a cabinet. more than enough for us, who were outside most of the time anyway.
We would definitely come again.