Thats sooooo awesome!!!! One of my good friends booked a
DCL and didn't tell her son. She woke him up real early for their flight and he had no idea what was going on! (he's only 9) Once they got to the airport in orlando and saw the ME check in he thought they were going to WDW then he said to her "hey this is a looooong ride to WDW" then he saw the Wonder and feraked out! SHe was sooo glad she kept it a secret. Good luck with planning and keeping it from the little ones.
P.S. I am soooo bad at keeping secrets I know i couldn't do it!