We are so blessed here with great places to walk/hike. Here's a great place to start if you want to hike in the Golden Gate National Recreation Area. Also, the Presidio Trust, and San Francisco City Parks (Golden Gate Park, McClaren Park etc) have many lovely trails, not to mention gardens for your walking pleasure.
Marin Municiple Water District as well as Samuel P.Taylor, China Camp and Mt Tamalpais State Parks. For Marin I highly recommend the Tom Harrison maps, during my vegetation mapping days I found them the most accurate and easy to use, and they cover all the parks/wildlands in a given area. They are available at many park visitor centers, and online at Toms site. Alas, due to budget restrictions, the State Parks are subject to closures, so check the website for specific parks before you head out.
|Tom Harrison Topo Map|