Sorry for the delay in hitting the DIS again, Elisa - I love WDW and would be more than happy to yak about it all day! My family is considerably older than yours, but we've been travelling to WDW for many, many years now - we honeymooned there, too! And we've gone every two years since our kids were tiny - of course, if it wasn't quite so far (or if we had more money!) we'd be there every year!
We drive, which may sound nuts, but is much more affordable and the kids have always been good in the car. Our favourite resort is CBR, but we've also stayed at POR and the All-Stars. Also, except for our first time with the kids, and our upcoming trip in the spring of 2006, we've always gone in December - more or less the same time you will be there, and we've stayed on site for Christmas, too! Ordinarily, we also rent a condo on a beach somewhere for week. I must caution you that there is a more than good chance you won't have a really good day for waterparks at this time of year - while we have been fortunate to hit warm days in Orlando in December, we have more frequently encountered cooler weather - great for the parks, and ok for the resort pools (in and out), but really too cool to enjoy walking around in a wet bathing suit at a waterpark for the day.
Please pm me or just use this forum if you have any particular questions!