Mark and Sarah's place was perfect for my trip to SF. They gave very clear and easy to follow instructions before I arrived on how to check in, and they were very responsive throughout the trip. It was nice to chat with Sarah and meet their dog for a little bit as well. The place is on top of Potrero Hill, so the views of the Bay are really great. If you're mainly walking around, note that coming back is a pretty good workout going up the hill. The room was spacious and clean, and the bed was comfy. No complaints at all.