Wow, just wanted to say thanks to everyone for posting their favorite memories, it is good to see so many different things that you all remember and hold as special.
I have 2 favorites:
FIRST-My dear Mom's first trip to WDW, our second--she needed to use an
ECV to get around and she was a riot on it. Joking with the bus drivers, offering to put other kids on her lap in line, etc...
We were heading to Muppetvision in MGM & there was a not many people around right near TGM, she took off (really fast) the wrong way. My DH runs after her & says "Ma, you're going the way!". She abruptly stops and says, "This is Disney World, who cares if I'm going the wrong way, I'll have fun wherever I am!!" and tore off to get in line for Playhouse Disney. Very funny to all of us & we still laugh about it. My mom passed away last month & still talked about how much she loved that vacation up until the day she went into a coma.
SECOND: Same trip, Sept 2001, my DS (then 4) was sitting on the curb during Spectro and he saw Snow White. He's never been "into" the characters, but loves to watch Snow White. He jumped up when she was headed our way and she stopped right in front him, bent down and held out her hand, he knelt down on 1 knee & kissed the top of her hand, then she kissed his! Just adorable
THIRD: Maybe not my favorite memory, but memorable to say the least. DS & I were waiting outside RnRC since he was too short to ride and DH was enjoying it. We were near a large group of vistors from England or at least somewhere with British accents.

My DS (then 3) was playing around, jumping here and there and ended up right behind a pretty teenage girl, decided to
pinch her bottom and run away! Everyone around us was laughing so hard, but the English group was appalled and said "What a dreadul little chap!" and "Did you see that, that's what Americans teach their kids!".
The funny thing is, my DH doesn't ever do that to me, so DS must have seen it somewhere else, probably in a line somewhere, because it would have been right in his sightline!

He's never done it since....