Before I say anything else...
What are you doing up this time of the morning, what is it 2 - 3 am there?
Anyhoo, there's a whole thread on the green mickey heads but it boils down to getting a classic mickey shape in a bright "home depot" lime green. Most people just print their own nowadays (I'd advise laminating it).
It doesn't have to be a specific size so if you've got a good color printer just run one off on a bit of A4/A5 (wait, you guys don't use the A standard, so A4 would be the 11 1/2 x 8 standard for printing letters, A5 is half that).
Then just pin it to something, turn it into a button, whatever floats your boat.
The idea being that when us DISers see a funky green mickey head in a color that Disney would almost never use, we know it's another DISer.
If you need a design template, go to that thread I mentioned and they have them on there. (Sorry I can't remember where the thread is, probably in community or just for fun).
Really glad you're going to Epcot, I didn't see it in your list. I consider Epcot to be the best of the parks (though I may be considered weird).
Assuming none of your kids are afraid of firewords/loud noises, definately go and see Illuminations. We're making it a feature of this trip by doing an Illuminations cruise, though we'll have lots of room to move around as we got a pontoon but there's only 3 of us!
Edit:
Here's the thread (or at least a thread):
http://www.disboards.com/showthread.php?p=35228619