All Boardwalk view rooms have some view of the fireworks. The higher the floor you are on, the better the view. Many standard view rooms also have a view of the fireworks. With these rooms, again, the higher the floor, the better the view.
If you want a Boardwalk view, it is NOT a request. It is a separate booking category.
If you want to be sure of seeing the fireworks from your room, be sure to book a guaranteed Boardwalk view. Request an upper floor near JellyRolls to have the best view. Those rooms are the farthest from the elevators, though.