Most listings are in the $50's per square foot per year. The Mill Valley region is going through a a boost in rates. In the last 3 months, the median rate went up $55 per sqft per year. That's a Inf% rise in rent.
Compared to the rest of the Bay Area market, the Mill Valley submarket has more expensive rates, and you'll need to make a great offer to be in this hot region.
In the last 90 days, 11 listings have been posted online, which means leases might be 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 posted, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 530 sqft. Most properties in this market are close to 2 stories. Most buildings in this area were built in 1964 and are Class A.