I usually tip the porters around $2-3 per bag rounded up so usually $15 for 4 bags. Same at the airport. In Belize a little different because I know "my porter" and he helps me get through customs without issues. I tipped our butler last cruise as there were 3 of us in the PH and he did some extra things like decorating the room for DW's 60th and made arrangements for a nice B-day dinner at prime 7. In the UK and Ireland, I tipped about 10 bucks per person for good tours.