Mill Valley is a small town in Southern Marin County, which is just North of Sausalito and at the foot of Mount Tamalpais. (Sausalito is at the opposite end of the Golden Gate Bridge from San Francisco.) Mill Valley got its name from back in the day when a saw mill was established in the center of downtown, which is now Old Mill Park. Mill Valley was a natural place for this since it is abundant with redwood trees, including Muir Woods National Monument.
Mill Valley is home the Mill Valley Film Festival every October, and many celebrities on a daily basis (Sammy Hagar, Bonnie Raitt, Danny Glover, Peter Coyote). If you're comin' to Mill Valley, you better have your sunglasses. With all the stars here, your eyes'll be burnin'.
Mill Valley's hills and downtown are covered with eclectic homes. Downtown in the flats, you will find (in addition to some more homes) the schools, shops (including my favorite market, Mill Valley Market) and restaurants like Piazza d'Angelo, Vasco, Small Shed Flat Breads.
The weather in Mill Valley can be cool and foggy in the summer time, so if you're headed this way, make sure you dress in layers.