I'd just get your own spot a half hour early. It depends on how busy the park is on the day you are going though.
I personally love grabbing a seat at the tables in Springfield facing MIB. The ones almost right across the water from the Jaws photo op. You get a great view of the big time fireworks that occur over MIB, a view of one of the water screens, and a wide enough view that the fountains actually add to the show all while sitting down in comfort.