A few years back we arrived at WDW late in the day 12/30 and departed 1/6......we did not see any significant decreases until 1/4.......however, I don't remember what day of the week NYD was that year.....in 2004 we arrived on NYD which was a Thursday and didn't see a decrease until Sunday 1/4 also. However, from 1/5 thru 1/9, our departure date in 2004, the place was empty except for people coming in the Disney Marathon which didn't really affect the parks all that much. We are going in January, 2007 also, but opted for 1/13 thru 1/20 this time .........probably a few higher attendance days due to MLK weekend. IMO the only drawback to going in January could be the weather.....we've had really good weather and really chilly weather......however, even in the reallly good weather it does tend to get chilly in the evening.......so if you are a family who likes to take advantage of water activities January might not be a good choice. In 2004 even though the weather was in the low 80's daytime DH and I didn't swim at all......our kids and grandson did go to the pool at BWV one day, but, didn't stay too long at all.