AJ's and Sundae Cafe are my two super fresh seafood go-to places, and both are excellent. They are located on Tybee Island, about a 15 mile drive from downtown and well worth the drive. They are both casual beach places.
For something fancier, they do seafood very well at Elizabeth on 37th, Garibaldi's in City Market, and the Pink House on Abercorn off the square between Broughton abd Bay. None of these three are, strictly speaking, seafood places, but they do speak the language.
Hope y'all enjoy your visit.