I think I may have stayed in one of the ten best rooms in all of WDW for seeing fireworks.
Our rooms (735 and 736) were on the seventh floor of the Swan, in the wing that sticks out from the main building (all rooms in these wings have balconies), on the Boardwalk side of the hotel. From our balcony we had great views of both Wishes and Illuminations.
For Illuminations, we were high enough to be above the trees and roof of the BWV and BWI and see the fireworks during the show that only go a few feet in the air. I've been in other locations (like the CBR and on the Boardwalk) during Illuminations and you can only see a few of the fireworks that are launched very high in the air.
While Wishes was quite a bit off in the distance, we could easily see the entire show. Yes I could tell which were launched from behind the park high into the air, and which were launched from Fantasyland and went much lower, but it was still neat to see. And it was very cool when we saw all of the fireworks that ring the park during the finale of Hallo-Wishes.
I think there are only a few rooms (less than 10) in all of WDW that could have good lines of sight to both of these shows. None of the Disney resorts are high enough to see both shows, with the exception of the Contemporary, which could only have a view of one or the other.
The Dolphin and Swan are high enough in some rooms, but angled in such a way that you'll only have a line of sight to one show. There's just a few rooms on the 6th and 7th, and maybe 5th floor of the Swan that have lines of sight into both shows.