questions re west coast usa trip

i will be flying into san francisco to start this trip next thursday, before moving on down highway 1 and across to las vegas via death valley before finishing up at joshua tree and flying home from lax. there are a couple of things i'd be grateful for advice on, as follows;

• i will be bringing my nikon d300 with several lenses in my lowe pro prorunner 300 photo rucksack - i know some attractions don't allow backpacks (i see on its web site alcatraz is one of them) - am i likely to have problems with this at many locations? (the hearst castle at san simeon is one place inparticular we intend to visit)

• will i need to take any particular precautions to protect my gear from the heat, say, travelling through death valley

• are there any specific suggestions/things i should be aware of fellow posters on here might suggest for my trip.

thanks