One of my favorite places in the world is the top of Mt. Tamalpais. It's a pretty short drive over the Golden Gate Bridge, just a few exits north on Route 1 in Mill Valley. You can drive all the way to the top and then walk around the perimeter on a paved path, or stop and hike at any other place along the way. And, it's just a short hop over from Muir Woods and Stinson Beach, so you could conceivably spend one day exploring the city, the beach, the woods, and the top of a mountain. Because I don't have a good camera and am taking photos with my phone, you can't see a lot of detail, but the top of Mt. Tam gives you an amazing bird's eye view of the whole Bay Area. It's amazing.