Weather is pretty much going to be identical still hot, though mid-October may be a few degrees cooler. We always found mid to late September the least crowded as school is back in session for everyone and "most" people are not going to take their kids out within the first month or so. Whereas, early to mid-October depending on Columbus day crowds could be a bit busier. Also, mid-October may pick up a bit for Halloween festivities. Either time, especially, September will most likely not be crowded except for the few days before and after Columbus Day, as always this could change but in past years this was my experience.