This is my favorite sky club in ATL. Weather you are waiting between flights or arrived in the airport early this is the best place to wait before or even after each flight. With and enclosed environment from the terminal .
This sky club is located down stairs near gate 27 on concourse d.. Down stairs they have plenty of comfortable chairs and power cords throughout the club.Work stations have computers and printers for though who don't have a notebook or tablet on hand.
The bar have limited seating with TVs showing CNN and ESPN. Service at the bar is ok. Occasionally the bar tender will step aside for 3 min. As all Sky clubs they offer free well drinks and domestic and free imported beers.Snarks are ok chips crackers hummus pretzels, cookies , carrots and celery during the day. Coffee machine  available to make late , cappuccino or just plain coffee.
COST
If you don't want to through 300-500 dollars a year in membership like me sign up with any of the amex delta cards to get free access or discounted enty.
Or pay 39 dollars for a one day pass upon check in through delta.
PROS
Free well drinks, Free beer
Simple snacks available free
Computer stations with printers
Comfortable seats
Helpful Gate agents
Power cords-- It can be tough to come-by at the terminal
free WiFi