Re: UC Davis or UC Santa Barbara?
You are a lucky man to have all those choices. They are all great schools. I went to Davis and loved it. I grew up in LA so going to Davis was a bit of a shock at first, but in a good way. As the other poster noted, there is not much going on there, but if your goal is to get good grades, that is not a bad thing. There is actually a lot going on there if you like sports (intramural, bicyling, etc.). If you like hanging out with friends, there are lots of good restaurants and coffee shops. The only negative can be the weather--hot in the summer, cold and foggy in the winter. But I even enjoyed the weather because it was different than what I was used to.
I have visited both Santa Barbara and Santa Cruz. I liked both campuses. As far as location goes, both are completely different than Davis. Yet they are still a bit isolated in comparison to say UCLA or Cal. Santa Barbara has a party reputation, and Santa Cruz has a counter-culture reputation.
Like I said, they are all great schools. I think you just need to figure out which one fits your personality best. Note that Davis is about an hour from San Francisco and Oakland, so it is not that far to go to get your music fix (and of course there is music in Davis and Sacramento too).