I don't know SQUAT about Hawaii, but I'm not sure I would plan the wedding vow renewal for your first morning, considering the possibility of delayed air, plus jet lag, etc., etc. Is that date your actual 30th anniversary??? If not, I might do it a different date. Cruise lines really know how to do those kinds of things. I might have a tendency to do that aboard ship, as you will not be having anyone else who needs to attend anyway. OR plan it yourself for one of your days aboard ship. You will be more relaxed, doing it later on.