So here are a few explanations we have used:
1) It's always a good idea for kids to write Santa a letter, and yes, emails are okay, too. This way, there's no question Santa will find them, even if their family is stuck at the airport waiting to board. (He might leave gifts at the final destination!) It's a good idea to have a grown up read the letter and send it for the kids, to make sure it gets to its destination. It's okay if the spelling isn't perfect or the handwriting not the clearest, because Santa has not only mastered EVERY foreign language of the world, even those no longer in use, he somehow has also mastered the art of reading even a doctor's handwriting. All he asks is children try their best.
2) Santa understands not everyone lives in a big warm house with a large fireplace and plenty of landing space. In fact, people have been living in apartments/condos/duplexes/townhouses/ca
Why, one year, Santa came to our front door and rang the buzzer, looking a little like a UPS driver, but with subtle hints that told us otherwise ;) Santa embraces technology - just ask the folks at NORAD who track him every year. I hear this year, he's even using GPS, so it's easier than ever to find good boys and girls.
3) Some presents come from grown ups and not Santa himself, which is okay; it means they care about the people they're giving gifts to. If a child hears that rustling in the bedroom and later finds a hidden present or two, that doesn't mean Santa doesn't exist.
4) The Santa Claus at the mall may not be the "real" Santa, but kids can be rest assured he's a close family member. Why else would there be such a strong family resemblance? There are over 6 billion people in the world, and Santa has to put in lots of overtime all year long to make sure all the toys are made. Plus, there may be some kind-hearted volunteers who are not related but are made honorary members of the family to spread good will to those who are less fortunate.
5) While Santa sure does love milk and cookies, sometimes there really is too much of a good thing. So perhaps changing up the offerings would make Santa especially happy! When our son was 8, he left Santa some pizza (Chicago deep dish, of course!) and one of daddy's favorite imported beers, thinking perhaps Santa would want grown up food to go with all the treats he got from everyone else. The next day, the plate was empty and presents were indeed left under the tree. Santa appreciates the thought, no matter what offering is left.
I've also heard Mrs. Claus appreciates it when more nutritious offerings are left, because she cares about his health. Kids who leave a healthy treat they also like are bound to be gobbled up before morning! And hey - the reindeer need a little fuel, too! They love carrots, hay and oats! Leave a mixing bowl of these goodies for them will be very much appreciated. If it's not too cold outside, a bowl of water would also be appreciated.
6) If for some reason Santa did not deliver the present a child asked for, please understand he tried his best. Santa is not infallible, but do know he truly does care for every good little boy and girl who believes in him, no matter where a child lives or what religion a child follows. Sometimes, even Santa can make a mistake. And sometimes, that super special, super hard to find perfect present was indeed hard for even Santa to find.