Go to TinksTravel dot com, they have hotel maps. (I can't get the hyperlink to work here for some reason!) You can click on GCH and find maps of the guest room layout.
We stayed in room 4022 (4th floor) and we liked it. It was a courtyard view, but we could see the high fireworks from our balcony, over the roof of the wing opposite the courtyard. We were also just 3 doors from the elevator, which made it very quick and easy to get around.
If you were able to get a DTD view in the wing closest to the end of DTD (for example 5419-5437 or another high floor) you would have a firework view, plus you would be able to take the stairs down to the "secret" fire door exit that comes out by La Brea Bakery, very close to the end of DTD and the security tents. It's locked, though, so you can only exit that way, and it would probably feel like a long walk to get back to your room by standard methods.
Hope that helps!