The BEST place, hands down is AJ's Seafood & Po Boys in the East Lake Shopping Center in Marietta. It's tucked in a corner, near the Kroger's.
The staff is friendly, attentive without being bothersome, and the food is the best. The menu is small, and still provides lots of options. There are some things not on the menu, but available, such as grilled shrimp or grouper, etc. You'll be greeted when you walk in, and thanked for coming when you leave. In between, drinks will be refilled (non-alcoholic) without asking and they'll check if everything is okay, etc. Then you'll be left to enjoy the food.
This is a small, neighborhood type place, so casual dress is fine. It gets busy on a Friday or Sat. night, and worth the wait for a table.
Have a great time with your friend!!