I remember when I first showed MLP:FIM to a friend. At first we started from the very first episode, however I don't think he was too interested after watching them. While the first 2 episodes were specifically designed to introduce you to the characters, the season 2 pilot episodes do a better job in my opinion. It's fantastic for establishing MLP's fantasy setting, which seems to draw in those who have the preconceived notion that the show is just "more of the same". Not only that, but I think it does a fairly good job of showing off the show's charm, humor, and characters.
Unfortunately, there is a bit of info that may not be fully understood without first watching the first 2 episodes, such as the history of Equestria and the banishment of Luna. You could just tell them about it yourself, that way you'll know if MLP is even something they would be interested in.Perhaps it would be a better idea just to make list of all the really good MLP episodes and show them that.