If you want to see the whole Bay Area in a single day, go to Mount Tamalpais State Park (801 Panoramic Hwy., Mill Valley, www.parks.ca.gov [1]). Always called Mount Tam by locals, this park boasts views of all nine counties of the greater San Francisco Bay Area [2]—from Mount. St. Helena in Napa down to San Jose [3] and across to Mount Diablo and the East Bay.
The Pacific Ocean peeks from around the corner of the western Peninsula, and on a clear day you can just make out the foothills of the Sierra Nevada mountains to the east.
Ample parking, interpretive walks, and friendly rangers make a visit to Mount Tam a hit even for less outdoorsy travelers.
Once upon a time, well-heeled visitors could take a scenic train ride up to and across Mount Tam. Today, you’ll probably want to drive up to one of the parking lots from which you can explore the trails. Take Highway 1 to the Stinson Beach [4] exit, then follow the (fairly good) signs up the mountain.
Links:
[1] http://www.parks.ca.gov
[2] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area
[3] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/silicon-valley/san-jose
[4] http://www.moon.com/destinations/california/san-francisco-and-the-bay-area/north-bay/stinson-beach