The typical asking rate per listing is in the $20's per square foot per year. The Vacaville region is going through a an increase in rates. In the last 3 months, the median rate rose $25 per sqft per year.
Compared to the rest of the Bay Area market, the Vacaville submarket has lower rates, so you should have no trouble finding a great deal in this undervalued region.
In the last 90 days, 1 listings have been listed, which means office spaces are probably going fast. You'll want to be prepared to tour spaces as quick as possible. 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 470 sqft. Most properties in this area are around 1 floors. Most buildings in this region were built in 1988 and are Class A.