We anchored off of St. Mary's and had a nice time for a couple of days. Pretty town. But for layover purposes, Brunswick GA is a much better choice. We like Brunswick Landing because it is a nice facility and right in town, which is charming and has some excellent restaurants. Ocean Petroleum right down the creek from there has some of the best fuel prices on the ICW and it is high quality due to being a high turnover commercial dock. Others like Golden Isles, I guess because it is not in town and also a very nice facility and a close car ride to St. Simons.
As for the inside outside issue, it is all about weather. If the seas are bad and the ICW was the right choice I'd turn into Norfolk/Portsmouth, not Rudee Inlet, or even on down to Great Bridge if the timing is right, with some great facilities and some of the very cheapest fuel on the east coast. The ICW is kind of pain from Norfolk through Great Bridge, what with bridge closures and schedules and the locks. From there on to Morehead City it is easy cruising if the Albemarle Sound and the Pamlico River are behaving themselves. A lot of people choose this route because distance wise it is the shortest.