So hopefully this will, if nothing else, make me feel like we're guiding them back in the right direction (away from the land of spoiled brat-hood) and give them a little context for why it is important to be appreciative of the people and things around us.
I feel that you are drastically over reacting.
And I think you said it right there...YOU are feeling a certain way, and by punishing them, YOU feel like YOU are heading in some other direction. This isn't about them at all.
Thank you notes are good. For, oh, 9 year olds. Under that, you don't get it. I was forced by my father to write thank you notes (for things that didn't even involve thought, so the thought did NOT count....stinkin' state spoons from my mean mean grandmother, for a little little kid) and it did not teach me a thing except I hated getting gifts while at his house!
In my house now, my son expresses appreciation every day. Not just a one time thing b/c he didn't meet my pre-set standard for reactions. On the 25th, his fave gift was very likely the bike my brother and SIL made possible. But his hugest reaction was to a $10 Power Miner
Lego set...his face was pure joy, he said he was so excited he couldn't breathe!
Kids are strange sometimes. They react in ways you can't understand.
But in this case, you are the one having a too-big reaction to something that doesn't show that they are spoiled at all.
Judging from your siggy, they've been many times - why would you expect them to be excited?
Seriously. At this point it's like going to the zoo for the 10th time in a year membership. They like it, they enjoy themselves, but they aren't going to go into a tizzy at the *thought* of it.
Stop it with the forced appreciation for all these things that have nothing to do with YOUR issue, and wait for the fun to begin when you are actually there AT WDW! You'll get the good reactions there.