We have been at WDW 3 times on the 4th. I don't remember any special events requiring reservations. I know that there were extra fireworks at MK. However, the year we were there the park filled up to capacity about 3 pm, so if you chose MK, make sure to get there early. Friends of ours went to the Studios, and said it was great, and not as crowded as MK. We like doing Epcot on the 4th. Illuiminations is followed by a great firework show. However, if you want prime viewing, be prepared to stake out a place early. We have seen people sitting 2-3 hours before the show on the 4th. It is a busy day.