Make sure to bring something along the lines of pepto bismol. I forgot medicine along those lines for a trip I took once and it was not a fun time. How long do you plan to be in California?
I'm probably going to get some stuff from the pharmacy to get me to sleep during the flight - I leave my home 6:00 am, and will arrive in the hotel some 18 hours later. One 11h flight, a transfer and a 2h flight. Seriously considering pulling an all-nighter Thursday just so I can sleep on the damn plane. Nevertheless, the experience and the people I'll meet will more than make up for it. I'm looking forward to stay there for 1.5 weeks!
I very rarely manage the dream of sleeping through a long flight and I've done some long ones. I'd advise against the all nighter just because if you don't manage to sleep through the flight you'll feel like absolute rubbish upon arrival. Anyways, I wish you luck and many happy memories. The places I've been to in California have been nice so I imagine you'll have a blast.