If you live on the East coast, the gay meccas would probably be Montreal. I feel it's both bigger than anything else on the USA eastern seaboard.
Visit both Toronto and Montreal for pride (Canada). 850,000 people in Montreal and 1,000,000 people in Toronto for the gay pride festivals. Supposed to be among the top 10 world's biggest; They film "Queer As Folk" in Toronto, even though it takes place in a USA city. (Yes, there's a real "Woody's" that people go to in Toronto and it's just like the one in QAF -- athough Babylon is a just a neon sign that the QAF filming crew brings in)
Yes, been to SF - I used to live near there for 4 months working in Concord. Beautiful place!