I just read from an old post here that when IOA was in development, they wrote concepts for several rides, including the Simpsons and Nickelodeon (which happened at USF), Casper, and PEANUTS?!?!
It was to be a show where the characters would act out holiday vignettes (like Lucy being the Statue of Liberty, which happened in a commercial for The Lady Foundation) in a school play, but things got out of hand, and Linus would clarify the true meaning of the holidays.
This would've been GREAT!! However, if Universal got Peanuts, then Cedar Fair wouldn't have been able to use them (just like Disney and Marvel.) I think the reason WB said no to Universal about DC and Looney Tunes was because of Six Flags. Universal Japan has Peanuts; so maybe this happened in a way??
I can imagine an alternate universe where it's Charlie Brown Christmas at IOA instead of Grinchmas. And from the looks of it, they would've gotten to use the TV special iterations (Cedar Fair can only use the comic iterations, which is why Vince Guaraldi never plays at the Planet Snoopy areas.)