Compared to the rest of the Bay Area market, the Santa Rosa submarket has lower rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 44 listings have come on the market, so you'll want to check back regularly for new listings. There aren't many listings below 2,000 square feet posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,610 sqft. Most properties in this area are close to 2 floors. Most buildings in this area were built in 1982 and are Class B.