1. What do you recommend we do while we're in SF?

Well, having played the tourist there recently when I paid a visit to Pixar, I'd say... leave. I couldn't stand it, and it definately would have drove me nuts if I'd stayed any longer than I did. That's a complete flip-flop from what I thought of it on my first visit. Be prepared to pay through the nose for parking. That said, Fisherman's Wharf was kind of fun. Alcatraz would have been cool, but I didn't go over. Golden Gate bridge, of course. Drive down Lombard a couple times. Don't know about the rest of the tourist/museum type things -- that's about when I went nuts from all the traffic and congestion.

2. What highlights of Northern California should we make sure we see in the remaining 9 or so days of our vacation? We're thinking Yosemite or Lake Tahoe. Any other suggestions?

I haven't been to either of Yosemite or Tahoe (I'll be there second weekend in September for a mtb race, though). Driving South down Hwy 1 is very scenic (same with going North, of course). That goes through Half Moon Bay, which is where Maverick's is (if the surf is up, it has 40-100 foot waves -- a widely known break among surfers). There's a lot of little B&Bs along the hwy that are pleasant.

If you don't want to go all the way north to see the really, really, really big Redwoods, there's Big Basin Redwood state park, which still has really, really big redwoods. It's off Hwy 9 and Hwy 35, between SF and Santa Cruz. The drive itself was a ton of fun -- twisty, windy roads.

Basically, the way I look at it is... buy a map of NoCal, and head for the green spots.

Have fun.