I was looking for a 2 night Fri-Sun hotel in September near CIA (the cooking school, not the spies) in Hyde Park and many of those closest to Hyde Park of regular hotel chains (Marriott, Hilton, etc) either have no vacancy or say no Friday check-in. First I thought possibly West Point football, but for only 1 of the weekends is there a home game. Any idea why hotels would be so full? Too early for foliage. Or any change anyone has stayed in a specific Airbnb near there.

It's too far from West Point to have any bearing on hotels on a football weekend. May be something going at Marist college, perhaps back to school or parents weekend or homecoming weekend. (Parents wknd is 9/27-29 https://www.marist.edu/student-life/family-weekend

And vassar family weekend is the week before that, 9/20-22. https://families.vassar.edu/events/weekend/

No other ideas, other than perhaps an early start to the fall peeping tourism traffic.

There's also a Holiday Inn express on Rt 9 just a few min south of the CIA. Courtyard by Marriott and I think a Hampton Inn in the same general area, and a bunch of chain hotels a few mi to the south at I-84 Ex 13/ Rt 9 in Fishkill.