Hi maps.....
We did the 'Ohana dinner in December and had a 5:10PS and the fireworks in MK were at 6:00. We did request a window seat which we got (not overlooking the castle but the Poly grounds....I guess I needed to be more specific!!) Anyway, when the fireworks began, the music was piped in and we were able to see just fine 5 tables away from the window!! Actually, the people sitting near the window allowed my 2 DS (8 & 4) to watch right next to window.
We have a PS for this trip at 7:50 and the fireworks are scheduled for 8:30! Looking forward to it immensely!!
Hope this helps a little!! By the way....the food is GREAT!!!