A couple suggestions: Napa Valley Expo in Napa or Sonoma County Fairgrounds in Santa Rosa is where we stay.
We have then driven our towed vehicle to the Larkspur ferry (north side of the bay) which took us for a pleasant ride to Fisherman's Wharf. From there we had pre-arranged a small van tour of the city. Here's the link:
Small Van Tour of San FranciscoIt was a wonderful way to see all the highlights of the city and had plenty of time to walk through the Japanese Garden and a lunch in Sausalito by crossing the Golden Gate Bridge. Even our daughter, who lives there, said it was a terrific tour! The driver was very knowledgeable and pleasant and we especially enjoyed the small group versus a big tour bus. At the end of the day we were dropped off at Fisherman's Wharf once again and we picked up the ferry back to our car. It was a very relaxing day! Have fun...