I can tell you what we normally do, We have been in April, July, September, abd December, and we usually pack the same. I see you are from NY so I doubt that 65 degree weather would seem frigid to you. I do take some capri type pants because I do not always like to wear shorts. I always take one pair of long pants for everyone (except me I use the capris) and everyone takes or buys as souvie one warmer top (zip up, sweat shirt etc...)
Otherwise we take all shorts and T's. I do not like to over pack and we still take and afternoon break/nap so I do one or two loads of laundry during the week. We find that we get hot and sticky so we often change clothes during the day, I just don't like to be all grimy and with the little one I always have dirt and food all over me, oh wait I have that even without him. This works out great for us and only one time was it cool enough that we had to wear the sweat shirt a few times and that was December and it was unseasonably cold (40's) Some of the attractions are cold inside and I like to have my warmer item for that sometimes. Have a wonderful trip. We are going on Oct 2 for a week.