I know this question was asked quite some time ago. I bought a waterfront home in Ocean Harbor some time ago for pretty much the same reasons you are now considering; with children in mind. My most important buying reason was the excellent school system which rates very highly on Long Island. The area is extremely safe and offers many healthy outlets for a young child many which are water related. Rockville Centre is where you will go to dine and shop with 53 restaurants many of which are very good. There has not been an influx of Manhattanites and not sure i would say it is "hip" but the quality of life is very good and that's the suburban tradeoff. If you are a true New Yorker you won't have a problem with a 45 minute RR ride to the city.
My house is currently for sale and is perfect for a young family. Feel free to contact me. Richard... more