My favorite was when I took my dgd, then 7, and my niece, 11, to see Anna and Elsa. It was my niece's first trip and she was thinking she might be too old to like Disney. (I, of course, knew better.) My gd was so excited, but my niece, being shy and a bit of a tomboy, was standing over to the side watching. Anna ran right over to her and gave her a giant princess hug and engaged her in the whole process. I am sure it was that moment that dn started believing in the magic.
The Mad Hatter put a booger on dgd once....she has never forgiven him.
And personally, I had a princess moment with Cinderella during the Electric Light Parade at the 24 hour event last year.
Character magic isn't always the big things like riding a ride with them. There is magic in the small personal interactions, too.