Most listings are in the $10's per square foot per year. The Brentwood submarket is experiencing a decline in rates. In the last 3 months, the median rate fell $7 per sqft per year. That's a 28% decline in rent.
In the last 90 days, 8 listings have come on the market, which means listings most likley are leasing quickly. You'll want to be prepared to tour spaces as quick as possible. 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 1,100 sqft. Most buildings in this market are around 3 floors. Most buildings in this area were built in 1965 and are Class B.