Take a look at the resort map. Marriott Grande Dunes is next door to Marriott Vacation Club's Ocean Watch. This entire property is under expansion and rapid development. In addition to the hotel, consider looking at the vacation options in a villa at Ocean Watch. Like Desert Springs, where my wife and I just vacationed (sans kids) Marriott Vacation Club next door to a Marriott resort always has something for the entire family!
Very nice hotel but why go to Myrtle Beach without kids?. Charleston, SC is a better choice for a vacation with a spouse. Great restaurants, lots of history and grown up night life in the prettiest city on the east coast.