Brookhaven and Buckhead areas put you pretty much in the northern heart of town. Dunwoody and Sandy Springs are just a few miles north of that. Marietta and Roswell are OK, but are a bit too small towny feeling. Alpharetta is a pretty area, but it feels a bit too far north sometimes. But Brookhaven and Buckhead puts you where all the pretty glass buildings and shopping areas are at.
The lower middle areas of town, Bankhead, Decatur, I wouldn't recommend. I would target the first four areas mentioned above, and wouldn't go any lower than Midtown.