I was Platinum when staying at the Hyatt Ziva but other than enhanced check-in and an upgrade to a pool view room there wasn't any different treatment throughout the stay. I would simply contact the hotel and request a king sized bed. We had the same problem and we were switched to a king before we even arrived there.

If you're the type that will get a good ROI at an all inclusive I'd stay at the Hyatt. The booze quality was good and you can ask for the top shelf stuff with no issues. The food obviously wasn't amazing but much better than some all inclusives I've stayed at. And the service was simply awesome our whole time there.