President's Day week is very crowded, especially over the weekend and until at least Wednesday. Not as crowded as Christmas or July 4, but crowded. But if you arrive at the parks early and use FastPass, you'll be fine!
Just got back from WDW over President's weekend and it was busy but very manageable. The Nat'l championship for Cheerleaders were there, Twirlers were there and Daytona was going on and the whole Northeast has a week off...but surprisingly we didn't find it too bad! (Maybe because we are AP holders at DLR where it is much smaller and does NOT hold crowds as well as MK!!) MGM was BAD on the cheerleading days because they have their competition at Indy. Sunday of Pres weekend was pretty packed too at MK, but FP is the only way to go! PLan and you can get everything in!