Myself and a friend stayed with Sandor & Guiliana mid March for less than a week, and we felt very much at home. They both have a great deal of knowledge about San Francisco and were so very helpful in sharing this and offering advice on sightseeing. Suggested by Guiliana, we took a walk through the palace of fine arts and Chrissy fields to get a view of the Golden Gate Bridge which was a really nice way to spend our last morning. With all this in mind, you get an idea for location, which they do have at a great advantage. Restaurants and shops are a 2 minute walk away to chestnut street and you can also hop on the 30 to take you to major tourist attractions such as Fisherman's Wharf. March is the start of tourist season so we were lucky enough to get tickets for Alcatraz at pier 33 which Sandor & Guiliana also guided us on. (If you're going after this time, book tickets in advance. Alcatraz is worth every penny.)
Be prepared to walk a few flights of stairs if you're coming with large and heavy suitcases, but I would say the wonderful location of this bnb overrides this.
All in all, I'm glad we got to share our first experience in San Francisco with such lovely people in their humble abode.