We loved our stay at Mark and Sarah's place. Our hosts were very helpful and communicative both before and during our visit. The apartment itself is clean, cosy and well equipped, with views out over the city and the East Bay. For a room in a shared home, it offered exceptional levels of privacy too - the room being on its own floor with ensuite bathroom.
We loved the Potrero Hill neighbourhood, with great options for food and drink on nearby 18th Street. We recommend Mac Daddy for an amazing mac n cheese! It's also just a short bus ride or cab to downtown SF and other areas, if you want to explore the city.