HI Emily,
My now 9-year old Son has always enjoyed spending time at the World Showcase part of Epcot Theme Park.
The
Kidcot Fun Stops which are situated in each of the 11 countries which make up the World Showcase has always been a favourite activity of his. Upon arrival at the Kidcot Fun Stop at the first country that you visit, each child will be given a souvenir craft on a wooden stick (on recent visits we have been given a Duffy the Disney Bear souvenir craft and Perry the Platypus souvenir craft) which they can colour in bit by bit as you travel around all of the different countries. A Cast Member at each of the Kidcot Fun Stops will stamp the souvenir craft and some will even write your children's names in their native language.
As an alternative, World Showcase Passports are available for purchase from most of the shops in both Future World and the World Showcase. This package includes a button, stickers for each country and the passport itself. You can take the passport to each of the Kidcot Fun Stops to get it stamped and signed by the Cast Members along with a special message in their native language.
I would also recommend that you try out
Disney Phineas & Ferb: Agent P's World Showcase Adventure which is another must-do for my Son when we visit. I'm sure that your children will love the idea of being a secret agent and you will be impressed at just how clever these interactive quests are.
Last but not least, you will find a whole host of Disney characters available for meet and greet around the countries of the World Showcase.
Wishing you a magical trip filled with memories which will last a lifetime!