Diane's place is very clean and has excellent access to many options of public transport at less than 5 minutes walking. Whatever you want to visit in SF downtown you'll find a muni stop close to their house.
They were very kind and their recommendations very helpful. They proved to be excellent hosts with a couple of problems we have during our stay that were not their fault but they helped to solve.
I'd absolutely recommend Diane's place as one of the cheapest and best places to stay in San Francisco.