This is just a big thankyou for the advice given. I've just come back from the trip and we had a great time (except for the traffic in LA - <img src="/images/graemlins/mad.gif" alt="" />).

The binoculars were a great suggestion, we saw so much wildlife! We decided in the end to make a detour to Yosemite National Park as well, and thanks to this forum, I had packed water treatment stuff, which we needed because we underestimated the amount of water we would need for a hike (we took 10 litres for 5 people and treated another 3 litres).