Diner's is not a bad card. I use it and the AAdvantage card exclusively. It is a nice option to have non-expiring points and the ability to transfer points to any airline and almost any person I want (except for AA, Air France and I think BA which requires that the milage transfer goes to the cardholder only).

The Card is beginning to be accepted more places in the US (I was in Japan 5 years ago and it seems like it was accepted everywhere there). All major hotels, airlines, gas stations, car rental and national food chains (Friday,etc...) take the card. FOr retailers, Barnes and Noble and I think Bloomingdales come to mind.

The best feature is the 60 day grace period. For example, my September statement (which end Oct 1) is not due until December 1 -- all with no interest charge!

Considering both are run by Citibank, I would use Diners exclusively if it was accepted more places -- I find customer service to be very friendly and helpful. There are occasions where I have found Citibank AA customer service reps to be downright rude. In addition, they are getting much tougher on receipt of payment -- if it is not paid by the due date -- $25 fee + interest (even if the bill is paid in full by the cut-off date of the bill) And to top it off, if you make payment at a Citibank ATM, you must make it 3 days in advance of the payment due date or it is not considered not timely paid. They claim it takes 3 days since the ATMs and Credit Card computer systems are not linked.

Sorry about the tirade about Citibank AA card -- if it was not for the miles, they would not be my card of choice.