To celebrate both my dad and I's birthdays, my family went to Kyma in Buckhead. It is by far my favorite Greek restaurant.
Kyma's fresh cuisine mixes amazing flavors together in a unique but refresing way. Our favorite was the fresh grilled octopus. I also loved the melitzanosalata hummus (with eggplant and walnuts). The restaurant serves tapas style, which makes it even better for sharing and sampling. Be careful, though, you can walk out with a hefty bill if you don't be careful! However if you're just looking to share a few amazing items, it's priced about right with tapas starting at $7.
If you like Greek food and drinks, this is definitely the place to come, especially with it's lovely atmosphere. The grilled octopus is the most popular dish on the menu, but you can also get whole fish for the table, sardines, all types of Greek foods like dormades and spanakopitas, oysters, and more. I'm not a big fan of the desserts because I don't like raw honey, but there's a banana dish that is superb (really only the banana part; the chocolate cake, which is flourless, is a little too dry tasting for my liking, but I did love the banana!).
You may also get lucky and spot a celebrity. For Kyma in particular, Vince Vaughn and Jason Bateman have both been spotted there. However, I would just go for the food alone!