Two things make SPG particularly worthwhile to me:

1) The upgrades I've received at key times, sometimes with the the advance help of a Platinum Concierge, have been enormous. A suite opening out onto the Grande Canal in Venice (on an award stay). . . another suite overlooking The Veneto in Asolo, yet another in Milan, a big 2-room suite every time I visit The Belgravia in London, same for the W Court in NYC. The list goes on.

I don't know my percentage, as I don't keep track. Frankly, for my stays at the Sheraton Newark, Sheraton Tulsa, Westin South Coast Plaza, Westin Michigan Ave., etc., I really don't care. I want a nice room with a good bed and I can always count on that. Perhaps I've been lucky, but when it has mattered (and I always let them know in advance when it is one of those times), they've always stepped up and I've had some of the best memories of my life thanks to SPG.

2) No doubt related to number one above, The Platinum Concierge. I had one I was in love with and she left SPG and I've worked with some others since. Still, their ability to help with a special occasion, an upgrade on a trip that really matters, and to just answer the phone when it rings and handle issues and requests competently and efficiently makes SPG stand out from the crowd.