I've been there often during President's week and it's not too bad. It was better years ago when you could just walk on the rides, but my last two trips 06 and 07 I have noticed that the parks have been a little more crowded. Your wait time on average is about 15 -20 mins ....the more popular rides may be a little longer. Having been there during spring break and the middle of summer - I'd take President's week over those time periods any time.
Yes...We will also be there starting the Thursday before President's Day and going back on that Monday...It will be interesting to compare the crowds to Disney..as we have been there for the past four years during President's week... We will be staying on site...so I think that will help...