When I hear "gated communities and new construction" I tend to think of the suburbs, particularly around Cranberry. I'd probably search there. Maybe Seven Fields.. also stretching towards Mars and down to Wexford and up towards Zelienople.. that entire area has lots of communities but they aren't necessarily gated, more cul-de-sac sort of living but it's a similar vibe as I think you're looking for.

I have no experience with Dallas and don't know what you mean by "master planned" though so can't be of much help on specifics.