From various posts I've read it seems that a lot of schools have breaks throughout October, although I think the first half is the busiest. And I don't think October crowds rival spring break crowds or anything close to that anyway so you should be fine. We are going Oct 25-27.
I have posted about dates too. I have heard that Columbus day weekend and sometimes that entire week are busy. Other than that I hear it is a good time to go. I am going 11th-16th, just the days that fit my schedule the best.
My kids have two weeks of school off in Oct.- the 8th-19th. We are going the 18-21st. We have tickets for Halloween treat on the 19th. I think it will be busy because there are a lot of schools on fall break and because of the Halloween festivities, but I don't think it will be as busy as spring break.
btw- we are in Northern CA.
We'll be there October 18-22nd! The schools near me are off like the first two weeks of October and my niece is off when we are going (she is in Sacramento), so who knows!
There never seems to be a super uncrowded time anymore, but I hear October is a great time to go!