I had been an American Express cardholder since 1979, and was a Platinum cardholder for the last 4 or 5 years, but cancelled my accounts last summer after being unable to get them to resolve a problem with a Membership Rewards travel certificate (Different blackout dates on certificate then on promotional literature) In my opinion Amex has evolved from a customer service oriented organization to an upscale marketing company.
I just can't see paying hundreds of dollars and not continuing to get the level of customer service that I had become used to.

On the plus side, since dumping Amex the amount of junk mail arriving at my home has dropped by over 50%!