Don't forget about head and tailwinds. Tokyo to SFO is 9 hours, but SFO to Tokyo is 11 hours. NYC to SFO is 6.5 hours, but SFO to NYC is 5.5 hours. More import

Don't forget about head and tailwinds. Tokyo to SFO is 9 hours, but SFO to Tokyo is 11 hours. NYC to SFO is 6.5 hours, but SFO to NYC is 5.5 hours. More importantly though, you can get to a lot of Asia from SFO without changing a plane, that's not true of NYC.