The only time I've ever shown the movies to anyone was back in Summer of '05 when a couple friends of mine decided to watch the OT since one of them had never seen it. I brought over my '04 set and we literally watched the entire thing in one sitting.

Now, when it comes to showing kids the OT for the first time, I think it's kind of pointless. I never had a "first time seeing the movies," not really anyway. I echo the sentiments of those who say that it will be hard to keep them away from seeing it until you decide it's suddenly time to show it to them.