For 3 years of sailing, I was based in the San Francisco Bay, on the estuary between Alameda and Oakland, right in front of Coast Guard Island. Actually, the estuary is more of a canal, but everyone calls it the estuary, which I think is how it started out.
The estuary is a nice, protected place for sailing in small boats, particularly if you keep to the east of Jack London Square, away from the commercial traffic. But for larger boats, the estuary is just the gateway to the San Francisco Bay, which offers a huge variety of sailing -- from gentle, warm, light-air drifting, to screaming along in a freezing gale!
It takes about 50 minutes to get from Alameda into the Bay proper; it's generally a case of motoring, since it's usually upwind, and tacking a large boat up a narrow channel through heavy traffic (it's pretty busy) isn't much fun. Once there, there's the choice of staying south of the Bay Bridge, in generally lighter winds (not always, depending on the wind pattern), or heading north into The Slot between SF / Treasure Island and Marin / Angel Island. This is where the big wind is, dependably 25 knots on a summer afternoon -- and a cold wind, too. But just to the north, around the back of Angel Island is Raccoon Strait, which almost always has very light wind and plenty of sunshine and warmth -- just an example of how the weather patterns vary in the bay.
The Bay Area sailing scene doesn't end on the water. There are plenty of marine businesses, who can supply all your boating needs, lots of yacht clubs, organized events, and more. Oakland is home to the Pacific Sail Expo, one of the major boat shows in the USA, and totally dedicated to sail. This is a really cool show, with a phenomenal number of boats on show, as well as 3 huge tents full of exhibits. There are all sorts of cool seminars, and the chance to meet sailing personalities and see their boats.
Oakland is a major port -- the 4th largest in the USA -- so, with the oil terminal at Richmond, and the various other ports in the bay, there's a lot of commercial traffic around. Since the big ships move at 15 knots in the bay, and need a lot of room, keeping a sharp lookout is essential -- the rule is, if you can see it, it's time to avoid it.
This is particularly interesting in the estuary -- which gives access to the busy Oakland inner harbour -- and which is barely wide enough for the larger ships to pass a small sailboat, especially if they have tugs in escort!
The port is also growing fast, with 10 new container cranes -- among the largest in the world -- recently delivered and commissioned. These were shipped intact, fully built from Shanghai, on a ship barely large enough for their bases to stand on. They had to pass under the Bay Bridge to get in, which has a clearance of 225 feet. After waiting for a cool day (they bridge contracts, and rises slightly), an extreme low tide, and stopping traffic to lighten the bridge, they made it -- by 20 inches!
One of the best things about the bay is that there are plenty of interesting places to sail to. You can sail from Alameda, round Angel Island, and back, which makes a nice day trip, and takes you under the Bay Bridge twice. Or you can cruise past Alcatraz and under the Golden Gate Bridge; or sail into the north bay, under the Richmond Bridge.
There's lots of scope for overnight trips, too. It's easy to sail to Sausalito, or SF, or Tiburon, take a slip for the night at a marina or yacht club, and sail home the next day. Then again, there are places to anchor, such as Horseshoe Cove, right under the Golden Gate Bridge; or you can take a mooring in Ayala Cove on Angel Island, which is a nature sanctuary, and well worth a 2 or 3 day visit. For longer trips, there's the delta, which offers 1,000 miles of navigable waterways.
The one dreawback of SF is that there aren't many destinations within easy reach outside the Golden Gate. In fact, the whole west coast of the USA, at least down to Point Conception, is generally hostile and inhospitable, with few exceptions -- such as the SF Bay itself. However, both Half Moon Bay to the south, and Drake's Bay to the north, are within a day's sail -- but with care, because the Gulf of the Farallones can be a pretty rough and scary place to sail.
But one of the nicest things is an after-work cruise, on a nice summer evening, on the estuary with your buddies.