Idealistically, I'm thinking maybe late September-mid November. September can still be very hot from what I understand. Aside from Columbus Day Weekend and major fall religious holidays which always change dates every year like Rosh Hashana and Yom Kippur, October seems to be the best month because of cooler weather and I've noticed a lot of fans like the Halloween Party much more than the Very Merry Christmas Party. Have to agree with the Watchmaker regarding Epcot during Food and Wine weekends. Things can get very crazy and feel like college party weekends all over again from what I've read and heard. November is also fine, as long as you finish your trip the week before Thanksgiving week.
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"All my life I wonder how it feels to pass a day, not above them but part of them.
And out there living in the sun, give me one day out there, all I ask is one to hold forever. Out there where they all live unaware, what I'd give, what I'd dare, just to live one day out there."