September? November?

[MonorailMan]

I've noticed that WDW has some of their cheapest hotel rates in September. The last time I was at WDW was the last week of November/first week of December....and the parks were almost "empty". The longest line I waited in was for Winnie the Pooh, and it was only 10 minutes. Some rides, especailly at Epcot, had no line at all. Spaceship Earth had a 30 second wait.....and Mission: Space had no wait. (We rode 3 times because there was literally no line to wait in.)

I guess what I want to know is: Is September really as slow as late November/early December? I just wasn't sure why November's rates are higher than September's if it's their slow season.