I have to be the first one to admit that Novato does not have a stella reputation public transport wise.
However, on the bright side, we do have Golden Gate Transit http://www.goldengatetransit.org/schedules/pages/Bus-Schedules.php
that runs through Novato and brings Novatans to the city (San Francisco), Sonoma and other counties - routes 51, 52, 54, 56, 58, 70, 71, etc. all runs through Novato
You really have to keep an eye out for the schedule though.
My husband likes to take the bus to Larkspur Ferry to the city.
There are airporters that bring commuters to San Francisco airports.
Sylvia Barry MAS, ePRO
Frank Howard Allen Realtors
(#1 Market Share in Novato and Marin)