Your best bet is to make your reservation for an hour before the fireworks are schedulede to begin. Maybe even an hour and half early. There is normaly a wait to be seated even with ps. When you check in you can request a window table, but they are first come first serve. Right before the fireworks begin, the lights are dimmed in the resturant and the music is piped in. If you don't have a window seat, you can get up from your table and go out on the oberservation deck to view them.
Good luck and have a great time.
Scott