Access to the Centurion Lounge is complimentary for Amex Centurion and Platinum cardmembers (who may bring along two guests). Other Amex cardmembers may purchase entry for $50. However, there are some reports that paid entry isn't offered at peak demand times or when the lounge is near capacity.
The Lounge is located on the second level of Terminal D at the top of an escalator
At the far end of the lounge there is a open bar and seating area. They have a number of specialty cocktails. I can recommend the George and Ginger.
The lounge also features a buffet with some pretty good eats. I was especially fond of the goat cheese and kale salad.
If you're coming off of a longhaul flight, you may appreciate the fact that the lounge features private shower rooms with L'Occitane toiletries. These are located down the hall from the front desk and can be reserved when you check in.
The Exhale Spa is also located down the hall behind the entry desk. Complimentary 15 minute treatments can be scheduled at check in.