Oh, the places you'll go!

I have had a hard time keeping my mind on my work today, as I am far more interested in planning our trip to California in a few week's time. We're landing in LA and driving up to San Francisco and we have planned that bit more or less (hotels booked, rough itinerary in place). From San Francisco we're driving to Yosemite national park, and I'm just looking at this stage of our journey - deciding how many days to spend there, where to stay, what to do.. ooh, decisions, decisions! All advice gratefully received!