I really appreciate all your thoughts.
Just one more thing: I am arriving from London into SFO, international terminal. Do I need to clear immigration in SFO international terminal (as opposed to another terminal or my ultimate destination HNL?)
If I clear immigration in SFO international terminal, I need to get back into terminal 3 to catch a United flight to Hawaii. Does it mean I have to go through the security screenings all over again?
Many thanks
Gerald