To put it simply, San Francisco is The Center of the Universe. Physically and culturally, it's halfway between Hong Kong and Amsterdam; Mexico and Alaska.
It's "The City" to locals, "Frisco" to tourists, but one thing remains for sure - you will not find, anywhere on Earth, a comparable combination of great food, ethnic diversity, architectural interest, natural beauty, easy sex or easy money.
Sure, it's got cold summers and absurdly overpriced real estate, but nobody's perfect..
I wish I still lived in San Francisco; Hayward's hecka boring.