Also, in your case, you also could consider getting a cabin ON the Lido deck. If you are on the Lido deck then you can walk right out to get coffee or a bite to eat and where they position those cabins is actually away from the traffic areas and is less noisy than you would think. You don't want to be mid ship on deck 6 which is typically above the casino. There will be noise there too. I'd stick to either cabins on Main or Upper middle (a few cabins away from the elevators like Sandy mentioned) or deck 7-9 (lido) near the elevators.
Carnival Cruise Lines:
Fantasy 90, Celebration 95, Victory 05, Conquest 05, Spirit 6/06, Freedom 6/08, Holiday 7/08, Victory 6/09, Valor 9/09, Dream 6/10, Splendor 8/10,Conquest 8/11,Magic 11/11,Triumph 4/12,Spirit 7/12,Freedom 11/12, Triumph 2/13 - The fire cruise
NCL Dream October 2006, RCCL Mariner OTS June 2007