I'm looking at the 22nd-27th of October. Was planning on the end of Sept, but seriously considering Oct because I'm afraid Sept will be too hot with a newborn.
I went over those dates last October, and I think the crowds would have been medium, but we got hit by Hurricane Wilma, so that changed everything. Many people from Southern Florida came up to Orlando, as lots had no power for weeks. But even so, I didn't think it was very crowded, but many things were cut back, since staff was needed elsewhere. And the parks partially closed one day.
We were chatting with alot of the South Floridians, who were telling us their stories, and it was very sad for some. I think normally it's a great week to go, as it's after the Columbus Day/week crowds. But it is still hurricane season, so keep that in mind!