I would think theres more noise in the middle of the ship as thats where the concentration of people are. Weve usually gotten a cabin near the aft and I can say theres less traffic back that way since the only people back there are ones who have a cabin there. We also prefer to be higher up since its closer to the pools, cafe, etc. When the elevators are jammed (another benefit to being aft since the midship ones get crammed often) its one or two flights up the stairs to the pool. As for the motion. we dont notice it unless its really rough. Todays ships are so big you hardly feel it, unless youre really prone to motionsickness.
PCL-Caribbean, Alaska, Panama Canal
12/02 RCI-Enchantment-Western Caribbean
12/03 RCI-Navigator-Western Caribbean
12/04 RCI-Mariner-Eastern Caribbean
12/05 RCI-Brilliance-Panama Canal