Well this is a good question, with no simple answer as it depends alot on the ship, generally I would choose a cabin midship and the higher the better, looking where the suites are and getting near to them seems to be a good guide. There are exceptions however.
To stay away from engine vibration and propellor noise etc stay away from the back bottom decks, the front of the ship you may hear the anchor being moved etc, being at the top of the ship may mean you experince the tilt of the ship, that doesnt bother me really though and its never been THAT rough on many of the cruises I have been on.
The location of show rooms has to be taken into consideration because you cant switch it off until they are done
Higher the better find the suites get near them and you should be alright