We've flown to Disney 3 x with our girls with another trip coming up in 3.5 weeks... this is the breakdown of what worked at each age:
Trip 1 (DDs were 2 and 4)
*Packed leapster and cartridges for the 4 yr old, portable DVD player, coloring books/crayons, snacks
*My then 2 yr old who NEVER napped actually napped on the plane ride down and back so her carry-on never got opened

She had snacks, books, her stuffed animal "lovey", etc
Trips 2 and 3 (they were 4 and 6 and then almost 5 and 7 )
*Leapster and cartridges for both, my ipod for them to take turns with, portable DVD player, crayons/coloring books. GUM!!!
This upcoming trip, they'll be 5 and 8.
*Nintendo DS and games, 2 ipods that play movies/tvshows with Hannah Montana and the Smurfs downloaded

, books.
**A tip that I got from here many years ago that worked great on their first 2 trips.... we brought 2 Mr. Potato head Potatoes down with us so that at the beginning of the trip, we went to one of the Mr. Potato head locations and filled a box to capacity with Disney parts. The pieces kept the girls thoroughly entertained in the AM when we were getting ready or if we'd stop back in the room in the afternoon to refresh... they LOVED making all sorts of combinations
For the parks, I pre-bought a couple of the battery operated misting fans that were an essential item last August!
Both girls LOVED trading pins~they each had a set amount of spending $$ and chose to buy lanyards and pins...
Older DD really got into the autograph thing last year-she was a character groupie trying to fill her autograph book

Younger DD wants to do it this year too
If you're staying on property and you are going in August, I highly recommend that afternoon break if you can. It's so bloody hot and humid that a dip in the pool would refresh anyone so that you can recharge for dinner/evening
Best advice: Don't try to fit everything in.... do it at whatever pace seems reasonable to your kids so you don't end up w/ meltdowns. Just enjoy the time together and try to make some magical memories
Have a wonderful trip!!!!!
