I met a doctor yesterday who was fresh back from a fellowship in los angeles, and did a big car tour around California. Though I've heard this before from Chinese friends, what surprised me was that he was much more impressed with Tahoe than Yosemite. Absolutely loved driving around Lake Tahoe. Guess you have to grow up backpacking the Sierra and revering John Muir and Ansel Adams to fully "get" Yosemite. In any case, I'd try to have both of those on my itinerary.

What's your jumping off point in California? Southland or Bay Area? Makes a big difference!

A ride over the Golden Gate Bridge would be awesome, and some stretch of the central/northern California coast like Big Sur or Sonoma County, which gets you into the wine country....

Maybe just spend the whole 6 weeks in California?