You don't have that many hours really, so pool is always a highlight for kids that age. Also, lots of shopping so fun to browse. It's fun to my kids to gets hot chocolate at Starbucks and pick a book/activity from one of the bookstores and hang out in the general bustle of the airport and read or people watch. Might be a fun activity to make up stories about people or families as most are there to travel: "look, they are carrying x, I wonder where they are/ have been traveling" as an example. In my experience,these kind of open ended questions lead to 10-15 min conversations, stories mostly created by the kids. Time will go fairly fast! Enjoy.