SPG Platinum, mostly traveling in Asia and Hawaii, is my only top tier hotel experience and am satisfied with the suite upgrade experiences. I would guess in the 75%+ range.
John over at
LoyaltyLobby.com has done an extensive analysis of various hotel programs and concludes that SPG is the most expensive program when it comes to redeeming points for free rooms.
Earning Points Conclusions
Burning Points Conclusions
How reliable are suite upgrades with top tier membership in other hotel programs and does is make sense to consider them when the primary concern is getting suite upgrades?