Cary's got to hold the world record for most "gated communities". Anywhere in the world would be better to finish raising your family in my opinion. They should change their name to Sprawlsville.
Of the three, I'd recommend Wilmington. Charlotte seems too big for what you aim to do, unless you and your family are accustomed to big city living. Wilmington has a charming downtown and waterfront area, is close to the beach, and hey, Dawson's Creek was filmed there: those kids turned out OK, right?
Interesting side note: some locals refer to Cary's name as an anagram (acronym?) for Concentrated Area of Relocated Yankees.