I've stayed here six times, some as Diamond, some as Globalist, I've spent tens of thousands here, including hosting our wedding (many of our guests stayed here too).

The only real upgrade I've gotten was on our paid Deluxe Ocean View to Ocean View Suite, as a Platinum (during HGP), during our first stay. (Interestingly, this suite was on the sixth floor overlooking the pool, smaller than the other Suites I've stayed in)

On subsequent stays I used Suite Upgrade Awards and was assigned the basic Garden View Suites.

I have successfully negotiated cash upgrades though to Deluxe Suites and one of their Presidential Suites.

Between those who are Globalist/Lifetime, those who pay cash vs points, those who are simply rich, and those who've stayed 1 time, 5 times or 20 times, (not to mention the simple question of how full the hotel is) I think one would have a veryyyy difficult time figuring out if there's rhyme and reason to any of it.... short of input from the hotel itself.