We bought passport books for the boys (ages 12 and 9), and they enjoyed getting them stamped at each country's station, and they also asked the CM's to write their names in the different countries' languages. Usually the CM's wrote little mesages in addition to their names, and it sparked some great conversations about the different languages. At several of the countries they gave the boys little cards with a map of the country on one side, and info on the other, and they'd write things on the cards too. I kept those for the scrapbook. I would highly recommend getting the passports - it gets the kids involved, and is educational without the kids realizing it! And we enjoyed talking to the CM's as well.
Our 2yo enjoyed the mask thing - she would color on it at each station, and at some of the stations they would give her special things like stickers to put on it, in addition to the paper things. In Japan, the nice girl made her an origami Mickey and taped it on her mask. So cute! The boys at first thought they were too old for the masks, but by the end of the trip they were doing them as well lol.
Sometimes the stations were easy to find, and other times we had to ask where they were. Mexico's is especially nice - there's a whole upstairs section with things for the kids to touch, and computer screens to push buttons on - they loved that.
Have fun!