Hi Anni
There will be a bit of variation in temperature but it's likely to be nice weather wherever you are. San Francisco will probably be around 15 degrees, LA a little warmer and Las Vegas possibly as hot as 30 degrees because it is in the desert. So I would pack your suncream and sunglasses, and maybe something warmer for the evenings by the coast.
You will have the opportunity to visit Alcatraz in your free time but you are advised to book a ticket online in advance. The best time to go is lunchtime or early afternoon on Day 2. You'll see plenty of comments on Alcatraz on the Community. Click on search (top right of this page), enter Alcatraz as a keyword and you'll see plenty of advice from other travellers.
Kind regards,
Olly, your editor