We were there 1-25 through 1-29 and other than DHS it was fine. We saw the most tour groups at DHS on Mon. 1-26, and it did worry me about how the rest of the trip would go, but then I realized it was the only night F! was showing so that probably had a large role in it. We saw tour groups in the other parks, but not in nearly such large numbers, and we did comment that it seemed without the tour groups that the parks would have been empty!
I would definitely go again late Jan. and was trying to get DH to agree to a trip in Jan. 2010 when the boys have teacher workdays, but he doesn't want to go when it might be cold (he was there MLK weekend and said it was chilly

).