Reading this forum I have to say I'm so glad most of my business travels are within East Asia. I'll breakdown by region of success to land a suite:
East Asia - around 40+ stays, I would say upgrade rate 90%, and the other 10% are genuine overbook situations.
USA - 10 stays, 3 upgrades, 30%.
Europe - 3 stays, 0-3, 0%
Middle East - 1 stay, nope.
So yes, it does seem like East Asia is treating elites better. With non-East Asian stays, most of the time I would check the app and I can still book a junior suite, so there's definitely availability.