CalTech, UCSF? Or some other.
Generally speaking, the largest obstacle to overcome in getting a job in Silicon Valley is obtaining an internship before graduation. Given the large amount of competition that many of these firms have, it is often impossible for someone with a short resume to apply and gain any special recognition among all the other applicants. As such, schools in close proximity to the valley such as Stanford and Berkeley are especially vaunted. The ability to get a local internship year-round cannot be understated, as one finds that schools such as Harvey Mudd beat out even MIT in terms of campus representation. Schools in California and Washington gain a particularly large edge here.
Beyond that, the single most important factor is on-campus recruiting. Schools with well-known programs such as Duke and Princeton make up for the distance by having the firms come to them instead. The general trend among some of the highest tier employers is to recruit at the most prestigious schools. This means that, outside of particular powerhouses like Carnegie and UT-Austin, the strength of the computer-science program in particular comes secondary to the general prestige of the university.
Schools with large alumni networks should also be given some considerable thought. While Caltech is prestigious, given the choice, Berkeley is likely better simply because of the number of current graduates that could lend you a hand internally inside of any large firm. This is why certain state schools can see some considerable sway even if the programs themselves are not the strongest.
In sum, look for a strong school in California. Stanford, Berkeley, and Harvey Mudd are your best bets, but beyond that, any decent prestigious program should do.