Something Tom hints at that needs amplification:

The hills! The farging HILLS! They look good from down below, they look good from the Bay, they make everything else look good when you're on 'em. Some have buildings, some are nice and green, one set sprouts a beautiful austere bridge to another, browner set 'o hills.

I grew up on congested Long Island; I find there's something utterly crushing and claustrophobic and directionless about flat, developed urban / suburban areas. I really got a kick out of Pittsburgh, the 3D city where I went to grad school, and San Fran, well DAMN, that's a city with lots of vertical relief!