I've been to Kyma, and while it sure was good, I prefer to kick it a little more casual. Have y'all ever been to Nick's on MLK? It's pretty sweet. The Blissful Glutton has a pretty solid review of it in this week's Creative Loafing.
And though they may not be straight up Greek, I'd feel remiss if I didn't mention Ali Baba's (Broad Street in 5 Points, Euclid Ave in L5P) and Mediterranean Grill (Virginia and Monroe, and then again in Emory). The baklava is killer at both places, and the food is as awesome as it is affordable.