Hello, Bonnie!
You are welcome for the information on Disney's Hilton Head Island Resort!
The link to Disney's Hilton Head Island Resort does provide a list of typical activities guests can expect, regardless of whether or not they are Disney Vacation Club Members. Contact the resort at (843) 341-4150 to get an idea of typical activities offered during the month of your stay. As August approaches, call back to hear the specific activities which are offered during your end-of-the-month stay, too.
The Dolphin Excursion was great for my almost 4 and 7-year-olds. The activity surrounding us was unexpectedly amazing (also late summer!) Get a kids' book about dolphins, or watch a show which highlights how beautiful and intelligent these creatures are, to enhance your up-close encounter. If you have a video camera with a wrist strap, bring it. You'll get some great footage of the dolphins, as well as your kids' reactions to seeing them in their natural habitats.
Back on land, Campfire storytelling and sing-alongs (with s'mores!) are great fun, and Sweet Goodnights (cookies and bedtime stories by the fire) are a surefire (pun intended?) way to settle those little ones in for a good night's sleep after an active day on the surf and sand. A favorite craft activity is Gyotaku ("fish printing"), during which they printed a customized fish T-shirt, using non-toxic acrylic paint. Book this early, as spaces fill up quickly!
A great UNOFFICIAL source of information is allears.net. Enter "Hilton Head Island" in the search bar and you'll find details surrounding readers' visits to this beautiful resort. This is not a Disney site, so all commentary is unofficial, but still helpful!
Enjoy your stay, and be sure to send me additional questions as you think of them! I'd love to help!