Bob Diamond, who pretty much runs Spinnaker sailing, is a Bay Area institution. He can tell you where every shoal is in Northern California, what the tides doing at any moment, and he can tell tales of adventures for hours. If you've ever thought about learning to sail, take the plunge (well not literally -- try to keep dry). Spinnaker is located in a part of the bay that is a bit easy on beginners, but prepares you for all the craziness the bay can offer.
PROS: Great sailing school with excellent instructors
CONS: some of the equipment is a bit older than the people on it