Well Mr. Itchie , I can tell you that Delta has clubs in Nashville (that I've never been to), Orlando (which is an absolutely magnificent facility), and Atlanta (Many clubs), but not Dulles, but most importantly I would think, they do have one in Raleigh Durham also (that I have not been to).

Your choice of clubs should really be driven by your primary airline of choice. If Delta is going to be your airline of choice, then you'll definitely want to go with them. One of the big advantages of having a membership is going to be the staff's ability to help you out of bad situations (cancellations and delays).