Am now in Barcelona, but thought I post our Boston airport experience. Arrive on United in terminal B. Most of the international flights are out of terminal E. I didn't remember this so we were a bit confused as to which bus to take to that terminal. Bus 11 and I think 66 both stop at all the terminals
Security lines were CRAZY. We were lucky as we were flying business, so got through security in 15 minutes. But the line for the masses was through the maze and past all the airlines check in area. Seemed to be moving quickly, but I would guess at least an hour wait, if not more. But terminal E is tiny in comparison to other airports, so once you are though security it's no more than a 3 minute walk to the farthest gate.
Anna, three hour layover is still plenty of time,
In response the the 3+1+1, if we didn't have to go through security after SFO, I could have buried my liquids in my carry on instead of an outside pocket.