If you do stop in Charleston, make sure you take the carriage tour. We were in Charleston and HHI last April and had just planned to do our own walking tour of the city. We happened by the spot where the carriage tours leave and were tired from walking so decided to try one. It was the hightlight of the trip (although it probably depends on your guide - ours was fantastic - entertaining and knowledgeable) - I highly recommend it! The drive from Charleston to HHI is a good 2 hours if I remember correctly and not a very interesting drive either.
When at HHI, we only ate at the restaurants across from the
DVC island. I don't remember the names, they were nice but nothing special. The shuttle from the DVC resort to the Beach House seemed to run quite often. Once, we walked back to the resort from the Beach House and it wasn't too bad - it was just the two of us, no little ones in tow.
The beach on HHI is wide and seems to go on forever; there were no lifeguards when we were there. The pool at the Beach House is a decent size but doesn't have a slide. There was hardly anyone in it one one warm, sunny afternoon. The last evening we were in HHI, we drove to the beach house to take a last walk on the beach and it seemed like the whole place was deserted. During an hour's walk, we probably saw 5 people and not a soul at the Beach House - it was very strange. I can't remember what time it was but it was open and it was still light out.
The pool at the resort has much better theming and the slide was open all day. That pool was quite crowded every day.
DVC on HHI is a great place! Enjoy!