We stay at the Park Vue, which is the hotel just south of the BWPPI on Harbor. We have watched them from their upstairs breakfast patio and the view was great! As long as you can see over Space Mountain, you'll see a lot.
We also fell asleep in our hotel room one night before they were launched, and the sound seemed 20x as loud compared to watching the fireworks from Main Street. It sounded like it was right outside our hotel window! I imagine it would be the same at the BWPPI.
Regarding watching them from the esplande.....not sure. But the view from DTD is not good. At least we have never found a good spot to see more than a glimpse.