I don't agree with Ducklite about seeing Illuminations only from a Standard room. We have had a Boardwalk view room (way down at the end, over the DVC office). We saw the Fireworks both from Illuminations AND from MK. We about got whiplash trying to watch it all.
Now that being said, you only see the higher ones either way. You can't see the water level fireworks of Illuminations. The MK fireworks appear to be the ones over the top of the Castle.
We have seen the MK fireworks before from a Boardwalk view room. It's a bit better view of those if you are farther down the Boardwalk, about halfway to the Green.
Oh, by the way, with a Boardwalk view room, you get a GREAT view of the ball, particularly at night.