On average, listings lease in the $70's per square foot per year. The Larkspur submarket is going through a decline in rates. In the last 3 months, the median rate decreased $4 per sqft per year. That's a 5% decrease in rent.
Compared to the rest of the Bay Area market, the Larkspur submarket has higher rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 9 listings have been listed, which means leases most likley are going fast. You'll want to be prepared to make an offer immediately. About 22% of the available space in the Larkspur are subleases, so you might be able to sign a shorter term by taking over a previous lease. 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 2,000 sqft. Most properties in this market are approximately 2 stories. Most buildings in this region were built in 1981 and are Class A.