The weather is a close second, I'm in Noe Valley which is really chilly and I like that. You should have people at your place and cook for them and call it a party, San Francisco has The Midway, Great Northern and outdoor activities at Golden Gate which are kinda "world class" partying but there's a lot going on in house parties and places of ill repute.
It's nice that it's not as warm as the south bay though.