Since we’re kind of on the subject, I’d really love to see a Sequoia version of the “Treetop Walks” like they have in the Karri Forests in Australia (and other places). I doubt they’d ever become a reality in the US because of the protected status of the trees.
Big Basin, while still heavily visited, may be a better choice for redwood viewing, and is still pretty close to SF. A breakdown on old growth redwood hiking:
As noted here, the giant sequoias are the world’s largest trees, in terms of volume, but the world’s tallest are coast redwood. The Santa Cruz Mountains in the Bay Area, where you’ll find them, may get a dusting of snow during winter storms, and may get a LOT of rain at those times, but chains won’t be an issue. Driving twisty, steep, narrow roads will. Just be careful.
Last summer we did a motorcycle ride in Michigan and a park we stopped at near Manistee had a few Giant Sequoias in it. According to this page the largest was planted in 1949 and is in the 90’ range.
We aren’t going anywhere near SF, so I think we’re most likely to take the van tour option of Sequoia. And I think I can get my sister and her SO interested in the pizza idea!