Hwy 395 is a beautiful easy drive for your motorhome. It gets you out of the heavy traffic on the western side of the mountains. Take it up to I-80 to get over to Sacramento and north of San Francisco and then take Hwy 101 (not 1) north. Traveling north on 101 you'll get into the giant redwoods. In fact, stay in Redcrest at Ancient Redwoods RV park right in the heart of them.
http://ancientredwoods.net/ For San Francisco stay north of the city along 101 at Petaluma KOA or in Napa at the Napa Valley Expo RV.
http://www.napavalleyexpo.com/rv-park.phpThen drive your car to the Larkspur Ferry Landing at Larkspur/San Rafael area on the north bay and take the fast ferry into the city. You'll ferry past Alcatraz. Pre-arrange for a small van tour of the city and they'll meet you when you get off the ferry. Even our daughter, who lives there, was impressed by the van tour. It will take you to all the major landmarks of the city, you'll drive across the Golden Gate and you'll have lunch in Sausalito along the waterfront. It will give you ample time to explore out of the van and about an hour or so to walk through the Japanese Garden. I highly recommend it.
https://www.sanfranshuttletours.com/