Where to stay in San Francisco?

This past June we spent a week at Marin RV Park in Greenbrae, just north of SF. It's nice and clean, but the spots are very small. Not a problem if you're going somewhere everyday like we did, but it's certainly not a place to have a campfire and sit outside. We enjoyed our stay because we found it very convenient. It was close to everything we were interested in. Most days we walked the 10 minutes to the ferry then sailed for about 30 minutes to dock right at the Ferry Building on the Embarcadero. From there you can walk to the various piers (very touristy) and the Alcatraz ferry tour. Or you can ride on a cable car or a streetcar. One day we drove to Tiburon and took the ferry to Angel Island where we biked the circumference of the island. Another day we biked across the Golden Gate Bridge (a wonderful experience!). There's no shortage of things to do and we were very glad we weren't way up in Petaluma, fighting traffic into the city every day.