I think over the past few years October and November have become more crowded. If you look at next year's 'seasons' November has gone from a value to a regular season.
I don't think you are looking at large crowds and waits. I went last October, it was the first time I had gone in October in about 10 years and it was quite a bit busier than I remembered.
The problem is you have so many schools going to year-round schedules, that there are very few 'dead' time of the year any more.
The real slow times seem to be September, January and first couple weeks of December.
I'm actually trying September for the first time next year, cuz the crowds are low and so are the rates. The offset is it's still a bit warmer and more humid than going later in the fall.