Living in Las Vegas, humidity to me is a "BAD" word for us which is one of the main reasons I love October in WDW. Less bugs too...LOL
We have gone during almost every month of the year for one reason or another just to get some kind of regular schedule going with our vacations years ago and have found the temps are perfect for us during that month and more important... the crowds are just right. You need a little bit of a crowd to make things interesting.. I mean half the fun is watching people in the parks making there way around the place.
We make most of our trips during the last 2 weeks of October, the evenings are very very nice, not to hot and not cool enough cause a chill. Because the humidity is MUCH lower then other times and the weather is great, most people are are not as rude or looking for a problem as I have seen during hotter months and when the crowds are there, at least that's how we see it.
You made a great choice as far as times to go... theres alot going on to enjoy all around.
HAVE A GREAT TIME!!!