For me, it's the little things that absolutely make Disney magical!
One I haven't seen mentioned - I LOVE the pages you hear as you ride the Tomorrowland Transit Authority! "Paging Mr. Tom Morrrow", "Please keep forward facing tentacles in the car at all times," etc. They always crack us up, even though we've heard them a million times!
I love waking up at the Boardwalk or the Wilderness Lodge to the sound of the Disney boats tooting their horns. What a great wake up sound!
And, though it's been mentioned several times, for me, the the ultimate Disney experience is Future World after dark - the sparkle lights in the pavement, the Fountain of Nations all lit up and dancing, that incredible music. To me, that feling is even more "Disney" than seeing the castle!