My cousin purchased her daughters small suitcases with their favorite Disney characters, put their magic bands inside, and wrapped them up. When they opened them, she told them the suitcases were to pack up their stuff to go to Disney World.
Have you taken your kids to Disney before? We have this old
Disneyland Fun Disney Sing-a-long tape that shows the actual characters (it's definitely dated and filmed in Disneyland - not Disney World - but there are similarities). Maybe you could watch that and then say you are going to go meet those characters at Disney World. Then both of your daughters will be familiar with the characters (not as cartoons) ahead of time.
Be warned though - you may get sick of it! Last night my 15-month son watched it 3 times in a row. I tried to put on a different sing-a-long after the second viewing, and he adamantly said "No! No... No... No... No... No!!!!" He then pointed at the DVD player and yelled "On! On! On!!!" until I put the correct sing-a-long back on.
We are going in Oct. and have ADRs at Garden Grille. I told DS we are going to eat dinner with Chip and Dale, and every time he sees them in the video now he gets a huge smile and goes "Eat! Eat!"