Compared to the rest of the Bay Area market, the San Anselmo submarket has less expensive rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 6 listings have come on the market, which means leases are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 83% of the listings in the San Anselmo are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 990 sqft. Most properties in this market are approximately 2 stories. Most buildings in this region were built in 1937 and are Class B.