We want to do Cinderella’s dinner but the times left are really late so we would miss MK fireworks.
Yes, you can see them from Grand Floridian from the beach area.
Not sure about any rooms, but you can watch from the Marina. The Narcoossee’s deck is also a great location.
Anything with a Magic Kingdom view will have a fireworks view obviously. Many lagoon views will as well - although you’ll want to check which lagoon you have a view of and the angle to the MK. We had room 8327 at Boca Chica which offered a nice enough view of the castle and fireworks, although the castle was framed by some trees. Here’s an example of a fireworks pic from the balcony of 8327: http://MaverickImaging.zenfolio.com/p565379316/e718f5065
Thanks for the info everyone!