...as to your actual question
The waiting can be excruciating. I'm feeling your anxiety, I've been there! The key to taming the ADHD brain is stimulation-enough interest gets the dopamine flowing, which enables self-regulation and actually slows us down. The art here is finding the right stimulation, which is not a science and can depend on factors like hunger and fatigue. But even with those variables, with little kids, especially in a new and exciting place, stimulation might not be as hard to come by as you'd think. A small handful of items, basic as they may be be, have gotten us through restaurants with 3 ADHD boys for 12 years now! I'm not gonna lie, it requires you to fully engage at a time when you probably need a break more than they do. But that's the price we pay for peace!
-Matchbox Cars. We would make a car track out of silverware and pass the car back and forth. If there was a paper menu (that was not useful as a coloring page) we would fold it like a tent and make it the tunnel. Can also be done with Thomas trains. Even better, when the table cloth is paper and you can draw tracks.
-Coloring. My mom hoards the small crayon boxes they give away at some restaurants. LOL This a great time to pick up a few thin and/or small Disney coloring books-help them find the characters they saw that day, etc... In the absence of coloring books, post-its provide endless entertainment. They can draw anything they want, and stick in on anything. Great for practicing letters-stick this F on the thing that starts with F...
-Stickers. So many options here. My kids love to put them on themselves (tip: double-check laundry!) but plain paper will often do. Or, go for the sticker books. There are countless, in all sizes. Disney theme would be great, as you could easily re-direct their attention to the stickers by asking about characters from the day, etc...
-Pressed Pennies. Now, this requires a little more investment, of both time and money, but if they get pressed pennies during the day, they have instant entertainment when they sit down to eat. If you get them each a little Pressed Penny Case, they can arrange their pennies, they can make crayon rubbings of the designs, then at the next meal there are new ones to re-arrange and make rubbings of. Now, this means you have to carry the cases, and bring enough coins to be able to get them each as many as you desire. You'll have to give this some thought and get the parents' permission. (If it's a go, it helps to bring a roll of quarters and pennies.) Then they have a great souvenir and a new collection too. My kids actually started their collection at the Statue of Liberty-this sort of thing transcends Disney.
-Just your eyes. Looking games, like I spy. This might not work everywhere, but so many of these places are so incredibly themed, there is eye candy everywhere. As you're walking in, try to notice interesting patterns, objects, etc... so that if you see a freak-out approaching you can cut it off with a quick redirection towards finding 3 blue things, or I see a picture of Pluto on that wall, can you see it?
-Hidden Mickeys. And this is for the whole park-ride and show queues, restaurants, resorts, even inside/during rides and shows. The Disney Imagineers have built the Mickey head silhouette into the art, architecture and design all over WDW. There is a book that tells you where to look. It's broken down by park, attraction, restaurant, etc so you can bookmark the pages you think you'll need. The clues are given in both difficult and easy versions, so you can totally do it with little ones. If you are waiting in a restaurant, you might be able to walk around with them to find hidden mickeys while waiting for food, given the right circumstances RE crowds, not disturbing other guests, etc.
Honestly, Hidden Mickeys are one of my absolute favorite things about WDW-we have a blast with it every time! I get the books at Barnes & Noble-they are updated every couple of years to keep up with park changes/expansion, so if you're interested, try to look for the most recent version.
The plane, I know is a different animal. Your flight is probably 2 1/2 hours? At least one movie, should eat up a chunk of time. Now, my ADHDers tend to ask for their same favorite movies over and over, but even though they insist on the repeats they often lose interest in them part way through. If you can bring at least one new movie that he hasn't seen, you have a better chance of keeping his attention for it's duration.
Simple hands-on crafts are good for plane rides too. If they will be having autograph books, maybe you can give them books that are blank and provide each of them with a set of pictures of the characters and a glue stick. They can glue the pictures to the left-sides of the page spreads and when they're waiting to meet each character they can look through their book to find the right picture.
Those bigger sticker books are great on the plane too. Games are hard, even travel-size, with pieces to manage, and even simple playing cards slide around... the possible "I dropped it" crisis just makes it not worth it.
I hope one or two of these suggestions sparks an idea you think might for your kids! If I think of anything else, I'll come back around!
