I've spent the last two months on Tripadvisor, but looking through some threads here, would be grateful for any ideas/tips etc. 
DH and I are flying in SF, and were planning to spend a couple of days in Napa before going to Yosemite for a couple of days, then driving through Death Valley to Las Vegas (one overnight - don't know where!). Our DC (22 and 23) are flying into LV to join us for the final 2 weeks of the trip.
Three nights in LV, driving to South rim of Grand Canyon to stay over one night, and then long day driving to Santa Monica where we're booked into a hotel for 3 nights (can't move this one). Then wandering up the coast and spending a final three nights in SF.
Not sure where we should stay in Napa. Need a gym, and an outdoor poor for relaxing would be lovely, although we will have a car and will want to explore a little. (Not too much - loads of driving during the rest of the trip!)
Second thing I'm struggling with, we are staying in Santa Monica for three nights, and we could then either travel up the coast road taking our time, or spend one or two nights in a more central position in LA (West Hollywood?), so that the DC will get more of the 'vibe'. Any thoughts?
Thank you for any thoughts/experiences on any part of this trip. I was last in California when I was 21, so things will have changed. 