The approach upriver from St. Simons Sound all the way to Brunswick Landing Marina is pleasantly deep and well marked. That's what comes from having a commercial port that in years past was also a hurricane hole for the US Navy. The one bridge span under which you must travel - the Sidney Lanier Bridge - is 125 feet high so pretty much anyone can shoehorn their cruising boat under it.
Sherrie and Cindy run the show at Brunswick Landing Marina and they are right on top of things. They are responsive to emails as well as VHF hails, and they will be there to talk you up the fairway and into their marina while their watch dogs, KIller and Danger,...watch. We arrived July 11, 2011, and Sherrie and Cindy took excellent care of us right from the start when they helped us dock. We were continuing our Great 10-Year Refit, and boy howdy did we have a succession of boat supplies shipped in to the marina during the 4 months The Fox stayed there. Sherrie and Cindy took it all in stride.
I won't bore you by listing all Brunswick Landing Marina's amenities; here's their website.