but I also have a Diners Club card (free).

How's that? I pay $89/year for my DC card.

The cost of the Amex Plat and President's Club membership is about the same. The Amex is a value when you consider that you can also go to Delta's club, and you get all kinds of benefits on top of it being a bling bling credit card. I had 2nd-row seats to see Guns N' Roses because of the card. I didn't even have to pay an inflated price for the tix.