Mole in Northern Marin?
Are you just looking to try mole for the first time.
In Novato, Sonoma Latina Grill has chicken in mole which is a decent enough intro
Chicken in Mole - Local chicken grilled over a wood fire then simmered in a Oaxacan mole made of a mild chile poblano pepper, peanuts, almonds, chocolate and traditional spices and herbs.
I don't remember if Karina's Mexican Bakery in Petaluma has any dishes with mole, but they do have a nice display of sugar skulls this time of year and a fair pan de muertos.