I didn't go to a UC school... but I'm on the west coast and my whole family is in Cali, so this is a tough decision for me too.
I interviewed at Harvard a couple of weeks ago, and it was awesome. All the students were laid back and super-interesting.. and the school just has so much money, that everything is cutting edge. I also really liked the societies. It's just also far from the family... Which might be ok. I'm not sure yet.
And i'll visit UCSF in a couple of weeks. The only thing I really know about it is from people I work with, who say its amazing, it would be their first choice, SF is great, but also that the environment seems "intense"?
I'd be curious to hear from people who have visited both and what they think the big selling points of each are.