Flew in and out of SFO last week. Arriving into the International Terminal G gates and taking BART is light years better than before (saves the never-ending airport train ride). However, arriving at the airport on BART without a pre-printed boarding pass (or if you need to check luggage) requires walking the entire length of the terminal to the check-in counters, which are right by the A gates. If your flight leaves from the G gates, you then need to retrace your steps all the way to the other end. Factor in at least 10 minutes for the round trip.