I vote Poly! It was the first WDW resort we ever stayed at, and my older son was 2; my mother and I went to Epcot for a late night, and my grandmother stayed back at the hotel with my son. All of a sudden they heard music and saw blinking lights out past the balcony - it was the Electric Water Parade floating right past our room! We didn't even know they had such a thing! Needless to say, my son and grandmother were delighted, and watched it every night together. We're going back in July to the Poly - my son is now 18 and just graduated high school; soon he'll be off to college, and we are all (including my grandmother, now 86) looking so forward to returning to that wonderful place. Maybe that's just nostalgia talking, but the Poly really does seem magical to us all.
Hope