Just a few things off the top of my head:
Magic Kingdom:
Remove that terrible speedway for Fantasyland and Tomorrowland Expansion.
Exterior Refurbs of Tomorrowland Buildings to bring them up to a more Sci-Fi Feel.
Replacement for Stitch's Great Escape.
New Daytime and Nighttime Parades.
Arcades on either side of Main Street for Traffic Flow.
Complete Re-Imagining of Space Mountain so it's on par or better than Disneyland's.
Significant Refurbs for Jungle Cruise (Adding Piranhas), Splash Mountain, and Peter Pan's Flight.
EPCOT:
COMPLETE OVERHAUL of Imagination. Gut the whole building. Throw away Everything but the Glass Pyramids.
Upgrade Fountain Technology in IllumiNations, but no changes for Pyro or Music.
Disney's Hollywood Studios:
More Cohesive Theme for Muppet Studios. (Re-theme Pizza Planet to the Swedish Chef, and throw in a What-Not Workshop)
Overhaul of Fantasmic! Upgrades to Sound and Lighting System, New Curtains and Backdrop, New Sequence replacing Lion King, Rapunzal Replacing Snow White in the Princess Sequence, Flotsam and Jetsam Boats for and Expanded Ursula Sequence, New Dragon, Technical Upgrades, Additional Seating.
Jack Sparrow Meet and Greet inside the Legend of Jack Sparrow.
Ratatouille Dark Ride from Paris and Ratatouille Restaurant in Pixar Place.
Complete Re-Imagined Backlot Tour with props from relevant movies, and queue through Disney Archives.
New E-Ticket Attraction Replacing Lights, Motors, Action (Tron Coaster? Stark Expo? Carsland? Something Else?)
Disney's Animal Kingdom:
Scrap Avatar
Expand Camp Minnie-Mickey to Include A version of Grizzly Peak, a classic Omnimover Dark Ride (Perhaps Lion King or Pocahontas) and North American Animals.
Orangutans, and Some sort of Orangutan based attraction for Asia. (Even if it was something small like a Spinner, or an awesome Play area)
A Walkthrough Experience for Dinoland, that would feature living character based Dinosaurs that could track your movements and follow you with their eyes. Designed to be educational about Dinosaurs, but still very impressive to walk-through.
Once All of that is done, a World of Color Type Fountain Show for Discovery River, using Everest as it's background similar to how Screamin' and the Fun Wheel are the background of WoC.
Those are just a few things off the top of my head.