@dogsdogs, @Jim_Iain, @DingoMom, @BettyCruiser, @kokopelli-az, @jelayne
Thanks so much for your responses!
I think my personal take-away is that if you already have a particular cruise in mind, there is some benefit to booking onboard, but the Book Later deal is no longer as beneficial. And conditions change so frequently I had better read the fine print of the LATEST flyer I get once onboard!