I have a new favorite place to take pictures and spot (which will become an even better place when the new International Terminal opens in Sept.) at SFO:
The United Express terminal. Board the bus at gate 87A (no need to be a ticketed passenger), and then enjoy the ride to the UE terminal. When you're at the terminal, you can either hang out in the bus loading/unloading area, or go inside the terminal, hang an immediate right, and exit out another set of doors to the outdoor terrace (I guess that's the right word!). You're extremely close to the new terminal, and close enough to the UA terminal. Be sure to bring your binoculars (for a REALLY good view), and have your telephoto ready.
All and all, it is a great place to spot!
F L Y 7 7 7 U A L