Hi, Elizabeth! I have used both
www.touringplans.com and
www.tourguidemike.com to help in the past in planning family vacations. I will say that as someone who has been to Walt Disney World in the hundreds of times, many of the tips and tricks I read on those sites are things I already had been practicing anyway, so they were not terribly useful in that regard for me. If you are relatively new visiting Walt Disney World, especially if this is your first trip, I would definitely recommend these services as a way to navigate the parks in a manner that optimizes your time for rides and attractions, and minimizes your wait time and stress level.
If you are thinking of going this Christmas, I would say sign up TODAY for something like
www.tourguidemike.com . The information provided is extensive, and the first time I used them, I printed out an enormous binder of information that I took with me. The other advantage to this site was the forums, where you can discuss your upcoming trip with other travelers. It's nice to bounce ideas off of each other, and you have the possibility of making new friends that you can meet with while in the theme parks.
I think these services are definitely more valuable during peak park times, and again, if you are new to Walt Disney World vacationing, they can give you insight into how to best lay out your days. I look at it this way. For some people, this trip is costing thousands of dollars, It's much better to spend just a few dollars more to make sure you have the best experience you can.
Have a great vacation!