I will "third" the recommendation for the Skidaway Island State Park. The sites are huge and beautiful, and if you want to visit Savannah, it's a quick hop onto the Harry Truman Parkway and you're there. As for it being hard to find, I found it not too difficult, and I was driving by myself. (Left the navigator at home! ;D) Once you cross over onto the island on Diamond Causeway, just look for the two huge churches on the left and turn between them. You won't regret it.
-Dave
<<edit: fixed a typo>>