With daughters aged 4 & 6 - I would bet they are into crafting!!
You will definitely need to allot a full afternoon for the World Showcase to make the masks. Personally, I would skip the Passports - my 5 year old, now 6, had absolutely no interest in this - boring - looks just like a real passport. She did enjoy the stamps - but the CM's will stamp the handle for the mask from each country, and will often also write a little message, etc., in their native tongue. Also, the Passports cost about $10 each, while the Masks - much more decorative and fun, are free!
My 3 girls have both Masks that they have done hanging in their rooms - they make an awesome souvenir - we also have $40 worth of Passports collecting dust in a drawer - live and learn!