We're looking for advice/local knowledge on the Sea Islands of Georgia as stepping stones up the East Coast by sea (not ICW). Information on good/bad anchorages, inlets, and such in Cumberland, Jekyll, St Simon's, etc would be welcome. We have a 6' draft.
Not really sure what your precise interests are -- simply navigation, or sightseeing, provisioning, repairs, etc.
That said, here's a little info towards your question:
Cumberland Island has a good anchorage. The main channel has lots of depth, and is well maintained to support the transit of submarines up to Kings Bay. Watch your depth as you ease East into Cumberland Sound out of the main channel into leading up to the sub base. There's a shoal that extends from the North that could cause you grief. Cumberland Island itself is very scenic, but short on amenities.
Best advice is to not try Jekyll -- St Andrews Sound is not all that well marked, and once inside you really can't go far. Jekyll Creek is very shallow and prone to shoaling, so making a short run up the ICW to St Simons isn't an option given your draft.
St Simon's has a long, deep entrance channel. Few anchorages once inside, but there are a couple of good marinas. Brunswick Landing has good facilities, good rates, is very protected, and is in a better location if you don't have wheels. Golden Isles is a little closer to the ocean, but is a little isolated.