On average, listings lease in the $20's per square foot per year. The Santa Rosa region is seeing a a boost in rates. In the last 3 months, the median rate increased $9 per sqft per year. That's a 47% increase in rent.
Compared to the rest of the Bay Area market, the Santa Rosa region has smaller rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 187 listings have been listed, so you'll want to check back regularly for new listings. About 3% of the listings in the Santa Rosa are subleases, so you will probably need to consider the implications of signing a direct lease with the building. 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 2,400 sqft. Most properties in this market are approximately 2 stories. Most buildings in this area were built in 1982 and are Class A.