I fly often between europe and NA, and I usually find the most options on Skyteam partners. Between Delta, NW and CO on one side of the atlantic, and KLM, AF, Czech, Al-italia, Aeroflot (and I'm probably missing someone) there are many different routes... although it can take some persistence with the agent, I'm usually able to find something. The fact that you're based in Atlanta makes Skyteam an even stronger option...