I like the 3 names in hat - each kid has the day to ride with you.
I would also buy 2 more of those little Mickey games like you got on e-bay. It does seem like you may have an issue with them getting too much/being unappreciative, but 1 game to share is setting everyone up for disaster. You can work on the appreciation issue later
And I really like the idea of not waiting on line with them. Let them wait and either don't ride or if it's easy enough join up with them right before riding.
(When my kids have acted up in the car, I have pulled over and gotten out of the car myself. I would never threaten to leave them or make them get out of the car or try to scare them, but I will tell them that I can not listen to their screaming/crying/fighting while I'm driving and I will wait until they are ready before we can go....and I will wait right outside car, where they can still see me and know they are safe (they are younger), but I won't listen to the noise. This works very well. they do stop when they are ready and we continue on calmly. Maybe not waiting with them will be similar.)
Also, the best parenting books I've read are:
* Siblings without Rivalry - Adele Faber & Elaine Mazlish
* How to Talk So Kids Will Listen & Listen So Kids Will Talk - Faber & Mazlish
* Kids, Parents & Power Struggles - Mary Sheedy Kurcinka
* Raising Your Spirited Child - Mary Sheedy Kurcinka
(Check out the above book firts, then read the Spiritied Child one, if applicable)
* The Parent's Handbook: Systematic Training for Effective Parenting (STEP) -Don Dinkmeyer Sr., Gary D. McKay, Don Dinkmeyer Jr.
(There are also versions for parenting teens, paretning young children , etc. byt he same author)
These are all very positive approaches to discipline, that focus on good communication, consequences rather than punishments, etc., very, very positive, and realisitic.
You might not have much time to read before the trip -- maybe 1 for the plane ride, for starters.
Good luck!