I just got back on Saturday evening May 28th from a week in a two bedroom villa at Hilton Head. It was perfect.
Do Disney's Low Country Dolphin Tour. It was absolutely wonderful. The kids loved it and so did their 49 year old father.
You sign up for the tour at the community hall right next to the Big Dipper pool. It is a good idea to sign up 24 to 48 hours in advance. The boat holds only 6 people, so generally it is just your family. This tour lasts about 1 hour and 45 minutes.
Tell them you want "Scott" to be your tour guide. He is very knowlegable. He also brings his dog "Woody" with him, a wonderful black lab. Woody sits on the front of the boat and is his official dolphin spotter.