Mark and Sarah were wonderful hosts! They were responsive and communicative and made sure I had everything I needed to have a comfortable stay.
Their place is located high up on Potrero Hill, so it has a pretty nice view! The downside is that if you intend to walk around you'll be hiking up hills, but at least you'll get a good workout! ;)
There's a main street with a bunch of cafes/restaurants/shops just a few blocks downhill, and it's a short walk to the Caltrain.