Then I talked to a friend who did exactly that a few years ago and he said it was awful. It's arguably the busiest week of the year (even more so than summer).
So my wife and I made the announcement as part of Christmas morning and took the actual trip the last week in January. Now it helps that our oldest was in 1st grade, so I had no qualms about missing a week of school. But it was GREAT. We waited for about 20-25 minutes for Toy Story Midway Mania, and that's the only ride we waited more than 15 minutes. Now that involved using Fast Passes of course. But wow, it was the way to go.
One more example; we went to the "Meet the Princess" attraction (not sure what it's actually called - you go through and get pictures with about 5 different Disney princesses) and literally walked up to the 1st princess. My wife about fainted, as I guess that's usually a nightmare of a line.