There are not too many better ways for a family to spend time then boating/wakeboarding/skiing. My kids weren't quite that young when they started (they were all over 10 when I bought the first wakeboard - an HO Perez) but they all had slalom skiied, kneeboarded and just plain grew up in the water.
Anyhow this is a picture from this summer, 2 thru college and 1 with 2 years left and they still come around.
Thanks for posting your experience it made me remember those days and it only get's better!
The family that plays together stays together!