I used to live in Shelter Cove (right next to the Dis DVC) and my dad has a villa on the beach in Palmetto Dunes that we go to every month. We never go to Sea Pines (the fee alone to get in is ridiculous). There isnt much there for our family that we couldnt find elsewhere on the island. You can walk all over Shelter Cove Harbour. There are neat little shops, a few restaurants, and many tours leave out of Shelter Cove. On Tuesday nights in the summer they have (I think they still do it) vendors set up all over the place, music for kids, and fireworks. There is also a little playground between Harbourside II and III. To get over to the beach (Dis has their own beach clubhouse) there is a shuttle. Its a short trip across 278 and through Palmetto Dunes to the beach. You could walk it, but it would be quite a hike! You can also rent bikes and ride around Palmetto Dunes and on to the beach.
If you have a car, Shelter Cove is pretty much the middle of the island. Theres a mall, and strip mall with a Piggly Wiggly, Fudruckers, pizza and ice cream places just up the street. Theres a mini golf right nearby too. The outlet malls are off the island (a must hit for great deals on kids clothes-Carters, Gymboree, Childrens Place, Osh Kosh.......). Google Tanger Outlet malls for Hilton Head for store listings.
Feel free to email me if you have any other questions about the island. I will try to answer them!