If you have more than one or two days to spend during your San Francisco visit, anywhere within the circle is about a two-hour drive. These are the most popular places for a San Francisco day trip:
A Day in Napa: Specially designed for a one-day trip originating in San Francisco, this itinerary lets you avoid traffic while you sample Napa Valley's wines, foods and scenery.
Santa Cruz: You may know about the Boardwalk and pier, but what about the butterflies and the historic mission? And the Wednesday night sailboat races?
Monterey and Carmel: It take about 2 hours to reach the Monterey Peninsula, home to the Monterey Bay Aquarium and 17-Mile Drive and a great locale for sea otter-spotting or window-shopping in cute little downtown Carmel.
The "Big" Trees in Muir Woods: They're the closest redwood trees to San Francisco, but not the biggest or the tallest. Check the guide to redwood forests in California before you decide if they're the ones you really want to see.
Take a Drive on the Coast Highway: California Highway 1 (the "coast" highway) goes north and south from the city and a drive in either direction is nice, but the drive you're visualizing may be far from San Francisco. Use the guide to driving on California's scenic Highway One to help figure out what you want to do.
More San Francisco Day TripsIn case you're looking for something a little different, try this list of day trips for more than 100 ideas. You'll find fruit orchards in bloom, a place to get muddy without getting into trouble, a sweet factory tour, a cartoon museum and some surprising artistic and architectural treasures, all within a day's drive of San Francisco.
Guided San Francisco Day ToursIf you'd rather have someone take you out for a San Francisco day trip than do it yourself, Viator.com offers a wide range of day trips to Wine Country, the Monterey Peninsula, Muir Woods, the Winchester Mystery House and even to Yosemite. For a more people-powered approach, try a San Francisco bicycle tour from the Golden Gate Bridge to Mt. Tamalpais.
Longer Side Trips
Yosemite National Park in One Day: Although the energetic traveler who starts early and drives back late could visit it in a day, it's really better to stay overnight if you're traveling from San Francisco - otherwise you'll regret making such a rushed visit and wishing you had stayed longer.