Disney has a plethora of characters they could use. I doubt they would use any they created with Pixar, although those would be very cool to see. Personally, I'd like to see a whole set of neighborhoods using their Winnie the Pooh family. That's Disney and Disney alone so there'd be no licensing issues. Or maybe just one playground called the Hundred Acre Wood, with streets for each character - Pooh's Playground, but Piglet's Pass, Eyeore's Avenue, Kanga and Roo Street, Owl Boulevard, Tigger's Tailbounce, etc.
Other possibilities include their feature films, all the way back to Snow White and Cinderella (Hey, a Disney Princess playground...but none of the males would want to play there

), all the way to Little Mermaid and Beauty and the Beast. They could do a Disney villain playground for really high level cogs, too, with Malificent, Cruella De Ville, Gaston, Ursula.
Really, there's no shortage of material there.
Gail