OK, I'll ease up on my hometown. Folks in SF eat out a lot, and there's a lot of restaurants given the population. So competition is fierce, and mediocre places soon die. So I will change "mediocre" to "pretty good". So the chowder in SF is pretty good, or even very good. But I love great clam chowder, and as much as I love SF I have to say the really good chowder is not abundant here.

I concur on the clam pizza. And A. Sabella's has very good chowder (but at $8 a bowl).

But it's really hard to find the GREAT stuff, something not partially out of an industrial-sized can. I'm talking fresh vegetables and plenty of big, healthy clams. It's just not easy to find. I think the best choices are a couple of raw seafood bars frequented by locals - Swan Oyster Depot (1517 Polk St., San Francisco, (415) 673-1101) and PJ's Oyster Bed (http://www.pjsoysterbed.com/). Be prepared for a wait, at least at Swan's.

As mentioned before, clams are not really a specialty of SF, although featured in a lot of dishes. The local fresh seafood are Dungeness crab (the season starts in early Nov) and salmon.

Many thanks to number_6 for much useful advise in the past, but I must say that:

Pier 39 is a tourist place and, as such, doesn't depend on repeat business. Like most places with such characteristics, food quality is not the highest priority because their main goal is to get people in, not to get them to come back. People that live in SF generally don't go to Pier 39 to eat (unless maybe at the crusty ol' Eagle Cafe). And, risking the wrath of this board, quoting a BBC food critic???