Hrollo's classification of Miyazaki's animated films:
Can be watched by young children > My Neighbor Totoro, Kiki's Delivery Service, Ponyo
Can be watched by brave, not too young children > Castle in the Sky, Porco Rosso, Spirited Away
Should not be watched by young children (unless you're the kind of parent who thinks "Watership Down" is an appropriate movie for young children) > Nausicaä of the Valley of the Wind, Princess Mononoke, Howl's Moving Castle
(I haven't seen "The Wind Rises" yet)