Just a thought about having a character come to the airport...keep in mind that other kids there will be clamoring to see the character as well, and their parents may not realize that it is a privately arranged meeting (especially if it is in the vicinity of Disney Magical Express). I'm not sure, but you may have to deal with parents who think that their children are welcome to ask for autographs, take pics, etc. Maybe you're OK with that, maybe not, but it is something to be aware of. And even if you don't mind saying, "no, I'm sorry, this is just for our family," having to do so may be quite a distraction from watching your grandchildren enjoy their moment.