Those of us over 55 are throughout Zip Codes 29464 and 29466 in Mt. Pleasant ( 29465 is reserved for P.O. Boxes). Most neighborhoods here have a mix of empty-nesters, singles, and families with children.
It may be easier to tell us what you are looking for (golf community, close to medical facilities, shopping, master bedroom on the first floor, etc.) and give us a price range and we should be able to come up with numerous homes in neighborhoods you might like to visit where there will be some others over 55. There is plenty to do here in Mt. Pleasant, SC for all ages.