I'm thoroughly charmed, and have enjoyed the movies. I think Princess Mononoke might be a bit rough for her intro to anime, but the other two work well. There's also an encouraging lack of groinal tentacles or free range mammaries, though I'm told this one advantage of watching Miyazaki.
Anime, a simplified viewer's guide:
Princess Mononoke: Think twice before you decapitate a god. (Admittedly an important safety tip.)
My Neighbor Totoro: Large furry creatures with huge teeth are your friends. (Somewhat countersurvival, that.)
Castle in the Sky: Always listen to your mother, especially if she's a pirate. (And who doesn't?)