I've never had an issue with noise at Boardwalk, especially in a standard room. It's been a while since I recorded this, so I can't give you specifics. I would just say to watch the section for the room category you booked.
Disagree that Fiji is "far from everything". You are steps from Captain Cooks, Trader Sams, and the rest of Ceremonial House (including monorail). And the views are far more beautiful than Aotearoa which is directly across the path from Fiji. Have stayed in 3 buildings at Poly and Fiji is my favorite!!