On average, listings lease in the $20's per square foot per year. The Santa Rosa submarket is experiencing a an increase in rates. In the last 3 months, the median rate rose $1 per sqft per year. That's a 3% increase in rent.
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 depreciated submarket.
In the last 90 days, 32 listings have been listed, which means spaces might be leasing quickly. You'll want to be prepared to make an offer immediately. About 3% of the available space in the Santa Rosa are subleases, so you will probably need to sign a longer term lease with the landlord directly. There aren't many listings below 2,000 square feet on the market, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,350 sqft. Most buildings in this market are around 2 floors. Most buildings in this market were built in 1982 and are Class B.