I am not sure of what you are really asking?
Are you looking for the best width and legnth design for San Francisco?
San Francisco is a unique city and homes are of all shapes and designs.
I would recommend a design that would accomodate your lifestyle and Don't overpay for average dollar per square foot in your neighborhood.
Two very important aspects in the price of homes: 1. Location 2. square footage of living space.
C 21 Agent 415-213-8220