Facebook: NY; Google: LA
The 2 most important, most trafficked sites on the web are the two largest, most important cites in the US - and they're as opposite as NY and LA are to one another. Facebook's social approach to the web is as foreign to Google as a good steak house is to LA.
Used to matter, not anymore - just trying to survive the exodus.
At one time this was the hub, not so much anymore.
Lots of flash and celebrity power, keep this one a favored destination.
This is where real people live: i.e. flyover country.
Wikipedia: San Francisco
Lots of smart folks working together communally to make the world a better place. Not to mention a few bad apples making the world a more difficult place.
Small, but very influential. Where the movers and shakers all start.
CraigsList: Las Vegas
Sin city - what happens here stays here (hopefully).
Old school, literally.
Did I miss any?