I don't think its the walls as much as whether or not your room has a connecting door. We had one at the poly and the sound from their room carried through the door. (Including a crying baby.) Just stayed at the YC with no connecting door and it was virtually sound proof. All YC rooms have balconies by the way.
Agree 100%!! The worst stay we had, as far as noise was concerned, was at the Polynesian. Stayed in Tokelau, second floor. Great spot. But, our room had a connecting door!! We had two different families there during our stay. The first family was a bit louder than normal...got louder as their time went on. But, they were there for just 3 nights. The next family??? OMG!!! Incredible. I don't know if someone had a hearing issue or if they were just very loud talkers, but we knew every single thing that happened next door!!! I finally had it when junior started telling nana, on the phone, about their day. I doubt nana needed the phone to hear him...it was as if he was yelling in my ear. He must have been standing right next to that connecting door!!!
So....I stood close to it, and yelled at my dd, 'Honey, use your indoor voice..there are people around us who don't need to hear you!!!' Now my dd hadn't even opened her mouth. But the neighbors seemed to have taken the less than subtle hint!!! They were much quieter. AND?? I quietly opened my door, stuffed a towel along the bottom and shut it again, and relocked it. That helped a bit as well.
I have stayed at...Pop, ASMusic, POR, S/D, Polynesian, CR, BLT, OKW, BWV, BCV, AKL, Kidani, VWL...I have yet to notice any difference in how thick the walls are. The one thing I do consistently do notice??? Toilet flushing from either next door or above. But, if you just close your bathroom door, it's barely audible. You do tend to hear people passing by your door more with interior hallways though.
Choose a resort based on it's theming and such..not it's wall thickness.