You can see the Magic Kingdom fireworks from the Contemporary, Polynesian and from the fort wilderness beach. In most of these places they pipe in the music into the public viewing area. I dont think you'll see it from many of the actual rooms though.
EPCOT has the nightly Illuminations fireworks and laser show. Best night time show at WDW in my opinion. You can see a few of the high fireworks from the Boardwalk Hotels ( yacht/beach club, boardwalk) but you really miss out on most of the show.
The Fantasmic show at Hollywood Studios also uses a good amount of fireworks.