Hi,
Not sure about the passion island thing, but you should really try to pick the night you want to dine in the reservations only and go up and make them there on the first day. They will fill up and it is less busy to do it on boarding day! When we sailed on the Spirit a few months back, I went right up there after we boarded and ate lunch on the lido -- around 12:40. There was no one else there so I was able to book the day and time that we wanted and that was it! If you wait until the day that you want to go it may be full. You'll love this experience!
