Seems like the trend continues to be that Mariner, Voyager and Navigator have the in-room champagne on arrival, but the Diamond and PG don't. But then there is Cindyr's experience on Voyager last September, where her champagne was from Amex. I guess the best we know is that the policy isn't consistent from ship to ship, and apparently in some cases not even on the same ship. So, as the kids say, whatever ....
