Was in Savannah just over a month ago and I would highly recommend that you go to Mrs Wilkes Boarding House.  The food there is outstanding!!!  Some of the best fried chicken you will ever have, succulent BBQ pork, meatloaf, lighter than air biscuits, all the southern sides you could possibly want and all of them very good.  You are served family style with 23 platters, bowls & dishes of food laid out on the table.  Youe will be sitting other people at your table.  Could be tourists or locals.  They only serve lunch from 11-2 and you will most probably have to wait in line but it is worth the wait.
 
On the road out to Tybee Island there is a little seafood restaurant that is super casual, very good and reasonably priced.  Great fish tacos and other items. 
 
Make sure you take the time to do some sight seeing in Savannah, a truly beautiful and historic city.  If you have time go out to Tybee Island and stop at Fort Pulaski on the way for an up close tour of a Civil War fort.