The aforementioned are class "A" inlets (marked and maintained for big ships). I have used Wassaw and St. Catherine's a couple of times quite happily in the past year. Both are well marked, and scenic. If you are nervous, go nearer to slack tide. I have also checked out Sapelo, which looks fine, but have not made the full transit, though shrimpers and many others go in and out of there. I have some time constraints on this year's northern journey, and may use all of these in the coming week, as much as I love the SC and GA ICW's beauty.
We had a great trip today from Addison Point (S. Titusville, at NASA Parkway bridge) to St. Augustine. I see no reason to go outside on that leg, as the ICW is pretty, straight and a minimum of speed zones. An outside trip would not save anytime, and I had been contemplating going from Ft. Pierce to Canaveral to Ponce to St. A outside after having done so from Fort Lauderdale to Ft. Pierce (which is DEFINITELY worth it). I'll decide in the morning whether to go out here to St, Mary's.. probably not as there are some beautiful stretches of ICW twixt here and there, and it is almost a straight line.
Two other Hatts here at St. Augustine Muni (do NOT stay here! Bridge construction noise all night), a beautiful 67 or so CPMY "Esprit D'IV" from Va. Beach, and a nice old 48 YF "Special K" from New Bern who I chatted with on the radio the other day.