One thing we learned from being on the Allure is that the Central Park balcony cabins are definitely much more quiet than the Boardwalk balcony cabins.
The CP area has all the trees and bushes to absorb the noise, plus there's just less traffic and less activity. Whereas the Boardwalk area does not have anything to absorb the noise and has alot more activity. While some of these cabins afford a nice view of the Aqua Theater, I much prefer the CP area for the quiet.
Just keep in mind that you're always on display with any of these balcony cabins, so you don't have alot of privacy. And you definitely have to keep the curtains closed, especially at night.