Wait a minute, SF Bay is one of the best sailing venues in the world. On top of that, it lends itself beautifully to spectating. It's like a giant sailing arena. I cannot imagine a better venue to watch these monsters sail. Watching the old AC boats on SF Bay was awesome; the multi-monsters will be better. The only reason Ellison wouldn't immediately bring the cup to SF is facilities/infrastructure, which is far superior in Valencia. If the infrastructure can be put in, SF Bay would be incomparable.
edit: ooo hobie1616 beat me to the comment.