Rather than just lurking, I thought I'd jump in here. To date me, I have had an AmEx card for 36 years. First green, then gold, and now platinum. I'm not sure how long I've had platinum, but it is at least 10 years. Each year I ask myself why I pay more than Gold, then I use one of the benefits and I don't revert back.
Admittedly, years ago the benefits seemed more useful. Before travel agent fees, I used them all of the time. Now I just do that myself. I have had business occasions to take my wife on 2-for-1 to Europe and rationalized that paid for at least 10 years of fees. Of course, on my own nickel, 2-for-1 would never be used. I do find the restaurant reservations, fine dining, and fine hotels a nice luxury and convenience in a hectic world. When I fly Delta or Continental, the club access is very useful. But it would be nice if the card covered more airlines. I have recently booked a cruise that will give me a shipboard credit and card credit that, at face value, equates to about one year in fees.
In the end, in a flash of honesty, I think I just like the self image of the status of a Platinum card. I am sure that is what AMEX wants. I have probably used enough benefits to pay for it thus far, but I almost canceled at the last fee increase. I can't say what I'll do in the future.
Larry