Most listings are in the $70's per square foot per year. The Larkspur submarket is experiencing a a rise in rates. In the last 3 months, the median rate rose $75 per sqft per year.
Compared to the rest of the Bay Area market, the Larkspur submarket has more expensive rates, and you'll need to pay a premium to be in this hot region.
In the last 90 days, 6 listings have been listed, which means new availabilities most likley are leasing quickly. You'll want to be prepared to make an offer immediately. About 183% of the available leases in the Larkspur are subleases, so you might be able to find a shorter term or below market rent. 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 2,290 sqft. Most properties in this market are around 2 floors. Most buildings in this region were built in 1980 and are Class B.