Another vote for Big Daddy's, if you're after oysters; owner also specializes in soup, and the burgers are good. Basic bar food done well.
Carrabba's Italian chain is here, but for a franchise, the service is outstanding, consistent, and so is the food.
If you guys want to drive a little bit, head to Senoia, to Maguires (http://maguiresirishpub.com/GreatFood/), Irish flavored and beautiful inside, along with good service.
Its another steakhouse, but Ted's Montana Grill is fun and tasty, especially if you like Ted Turner! :) http://www.tedsmontanagrill.com/ He's raising bison and offering that aside regular beef and chicken.
If you want a wider range of seafood in a nice environment, The Georgia Shrimp Company is a great option (http://www.georgiashrimpco.com/). The owner, from South Africa, does amazing things at reasonable prices.
Not much here, but just went for the first time to Big Daddy's Oyster Bar (in the Fresh Market shopping center) and was pleasantly surprised...seafood-y, dive-bar, type place...fun and decent food. Otherwise, it's pretty dismal with all the chains. There is one independent place - Pascal's Bistro. Very nice.
If you are willing to drive a bit, try the restaurants at Serenbe (The Hil or The Farmhouse) or Founder's in Senoia.
217 Commerce Dr, Peachtree City, GA 30269
Big Daddy's Oyster Bar
101 Crossings E Ste 3, Peachtree City, GA 30269
9110 Selborne Ln Ste 110, Palmetto, GA 30268