Do any hotels in the parks have a ballroom or a event room you can rent out for a few hours for a party? Like the ones some Holiday Inns have? Thank you for any advice! 

Pretty much any attraction, land, even an entire park in WDW can be rented out for a private event. All it takes is a lot of Benjamins.It's not in a hotel, but I've seen the American Adventure pavilion rented out for private events. It can't be cheap, though.
Coronado Springs, the Contemporary and the Grand Floridian all have convention facilities. I haven't personally seen any of these, but most venues capable of hosting conventions can usually accommodate smaller groups.
And this is the wrong resort, but I know the Grand Californian Hotel in Disneyland has several options, ranging from standard convention rooms, a decorative courtyard and a poolside patio.
Yacht Club and Boardwalk do too, as well as the Dolphin.Coronado Springs, the Contemporary and the Grand Floridian all have convention facilities.
It's not in a hotel, but I've seen the American Adventure pavilion rented out for private events. It can't be cheap, though.
Coronado Springs, the Contemporary and the Grand Floridian all have convention facilities. I haven't personally seen any of these, but most venues capable of hosting conventions can usually accommodate smaller groups.
And this is the wrong resort, but I know the Grand Californian Hotel in Disneyland has several options, ranging from standard convention rooms, a decorative courtyard and a poolside patio.
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