It has not been asked so we'll try and answer that. I tried (and failed) to bring the DLP Dragon (enhanced with speech, real fire and more of a dramatic show scene) to Disneyland as the finale to a revamped Sleeping Beauty Castle Walk-thru. An anniversary enhancement. So I guess the Dragon would be my "one thing" or top import, as the Castle at DL has such a modest payoff for it's iconic status, and DLP's Dragon is still a real hit.
Maybe as alternates, put the Toad Hall Restaurant into WDW Fantasyland as the ride is gone. Nautilus Walk thru would be nice at DHS as a "movie set". Would love to see Arcades added to the Main Streets as it's awful to make guests walk through dirty backstage areas after parades to leave the park.
I remember eating at the Toad Hall Restaurant years ago at DLP, it is very nice, plus since I love the attraction, it has all sorts of nostalgia. Thanks for the links to pics, brought back some good memories!
Before I read this post I was going to bring up building a Mr. Toad restaurant and attraction in the Magic Kingdom. They took out the old Mr. Toad ride, but with the new movie, and obvious love of the attraction, I think an updated Toad attraction would last for decades, especially as an E-Ticket.
The ride entrance could be a large Toad Hall with one side for a restaurant/viewing area of part of the ride, as if you're looking out on London at night, and the other half the entrance/exit for the ride. They could build a longer, and slightly faster, Toad, without necessarily the cost of a test-track type system. I love how Radiator Springs Racers uses what looks like fake plants in the dark ride section, instead of flat plywood cut and painted to look like plants. (I haven't ridden it yet but have seen the YouTube videos). And RSR also seems to use a lighting system that makes the inside look like the country side basked in moonlight, without the use of UV-dark light. I
love how this effect looks (no doubt some mix of blue light), and think it would be great for an indoor Toad ride. A large show building could add a lot of scenes and flesh them out more effectively.
There seems to be plenty of space behind MK's Pinocchio Haus, which is kinda dated looking, a Toad Hall restaurant at least would be great. Disneyland's Toad is done right, its fascade is actually based on the Toad Hall in the Storybook Land Canal Boats. It would look great in Fantasyland in MK, though would also fit in the United Kingdom part of World Showcase.
Regarding bringing DLP's dragon to Disneyland's castle, I would assume that this would involve building a grotto where they are putting in the princess meet and greet. It certainly would have plussed the walk-through.