We were in 4115 2 BR SV ,it was oppisite the bus stop. We could see all of the high fireworks and could hear the music like it was coming from the boardwalk. A great room ,if you don't mind the walk. On the plus side it only takes a minute to get to the quiet pool down the stairs.
I've never had a boardwalk view (yet!) but we had great Illuminations views from the 3rd or 4th floor of standard views down on the end near the pond. If you look straight head from there, you can see the Eifel Tower and the top of the American Adventure. Our last trip we had the corner room and could see both Illuminations and Fantasmic. You can ever hear the music!