Apparently there is a great science in reserving just the right room on a cruise ship. This can be seen in the huge varieties of room pricing when you try to book a room. For our cruise they varied from $1299 to $3000 a person. (I also read the penthouse cost $30,000)
From the research I did the biggest things that people tried to accomplish is to disguise the fact they were on a boat. To reduce the rocking of the boat normally you want to be as low as possible but with newer ships with active sway suppression it is better to be near the middle. Noise is the other big problem. Engine noise is higher for lower decks and further the cabin is in the back.
Higher decks are closer to attractions, and I read repeatedly (and it was true) that the elevators are slow so you use the stairs a lot. The other type of noise you try to eliminate is other people. You don’t want your cabin above or below restaurants, the casino, weight room, or pool; and you don’t want to be next to stairs or an elevator.
For us, our cabin was on 9th of 14 levels. All the stuff was on the 7th or 12th floors so we had buffer floors to cut off the sound and we were one cabin away from the stairs. It worked our cabin was quiet.
The other stuff I didn’t read about that ended up mattering was getting a window or not. We got an inside cabin because of price but I was afraid our cabin would be to small so I got a four bed cabin thinking it would be bigger. It ends up there was just a bunk bed attached to the wall and a trundle bed under our bed. But our bikes fit next to our bed and our luggage in the closet so we were happy. It ended up being a very good thing to get an interior cabin since we were so far north it never got dark at night. Neither of us would have been able to sleep with the light coming in through the cracks in the curtain. With no sound and no light it was disorienting when we did wake up. To get around this there was a channel on the TV in our cabin that was from a camera pointing out over the bow of the ship. We referred to this as the window and turned it on to see the progress of docking or to check the weather before heading up to the hot tubs.
As the trip went on I was really glad to not be in the lower cabins. On the lowest level (deck four, everything below that is engine or storage I guess.) there were no opening windows so there was a strong smell of chemicals and diesel fumes. Also to have everyone marching past your cabin for every port while you are trying to sleep did not sound fun either.