I spied the Galaxy Diner a couple of weeks ago and finally got the chance to try it. It's on Chamblee-Tucker Road just north of I-285. The interior is very homey. The big feature is the huge collection of car photos, which were taken during their Saturday night car rallies. (That sounds like a fun activity...)
The food is classic diner; I had the turkey dinner. What I really enjoyed about the Galaxy was the warm and friendly service. Everyone was extremely nice and helpful; the owner even came over to say hello and adjust a fan. As with all real diners, their dessert selection is vast with huge portions. I tried the devil's food cake and was very happy.