All W's in the US preblock platinums/golds prior to arrival. They run a report of all incoming guests the night before and upgrade the morning of arrival to whatever is available. So arriving at 9AM or 9PM most of time doesn't matter as you will be upgraded. Now there are instances where rooms are taken away after being preblocked but that happens. If you want to try your best chances, stop by the hotel at noon and pre-register and negotiate and see if a better room type is available at that point. I have been upgraded at each W in the US to a suite and none of the standard upgraded suites have jacuzzi's. I wonder which W you are referring to. If it's an extreme or WOW suite you can almost forget that upgrade unless you get it from a manager. Good luck!