I'm currently at Shem Creek Marina, and the operation there is top notch. The facility is nice, the location is great, and the service is very very good.
I was at Daniel Island Marin for a few years and it was also very good. The only reason we moved is because most of our boating is behind IOP, Sullivan's, Capers, Dewees, etc. and Shem Creek is much closer.
I worked at shem creek marina for three years. You can't find a better location or a better group of guys looking after your boat. They are all very knowledgeable and willing to help. My dad also kept his boat there until he recently sold it. The marina's number is (843) 884-3211. Ask for the Shane the dockmaster.