I went to my Dad's 25th reunion at Harvard when I was a kid and it was beyond fantastic. I stayed in Dunster House, alone, but was too scared to sleep. I went out to the quad where guys were playing soccer by streetlight. They put me in the game and let me score a goal, and carried me off the field on their shoulders. The kids got a trip to Fenway, and the beach. I palled around with another kid and we wandered into a band practice room where we hung out for hours, to the point where no one knew where we were. I remember a big picnic, lots of big tents, and hundreds of people from different clashes. One of the great weekends of my life.
I have never been to any other reunion.