Originally Posted by
andreiz
I assume the checkpoint at T2 will not let me past with the UA pass (it's an American/Virgin America terminal).
The regulations technically allow you to enter any terminal as long as you have a same-day boarding pass originating from that airport, but in practice you can have some difficulty. While I wouldn't advocate for being untruthful, there is an Admiral's Club there, and I've had good success using airport clubs as a reason why I need to be in the United terminal when flying WN.
Also, you already seem pretty familiar with SFO, but don't discount the pre-security options in the International Terminal, or Yankee Pier post-security in Terminal 3. I had one of the best airport breakfasts I've ever had at Yankee Pier.