We were just in 2638 and 2640 a couple of weeks ago. The rooms were very nice. You are only a very short distance down the hall and up the stairs to deck 3 that has a lot of activity - internet area, promenade lounge, animators etc. As a matter of fact, the wireless signal for my laptop died just as I got to my room - so others closer to the elevator from 2638/40 may actually get a wireless signal in their rooms.
As far as noise goes - when the ship is throttled up close to cruising speeds (20 kts and over), you will hear a very low frequency hum from the engines - this is not a big deal at all - you get used to it very fast, and it is not unlike other white noise that you might get from airconditioning in homes, offices and hotels. (as a matter of fact, white noise can be good as it masks other sources of noise)
You will also hear/feel side thrusters that may wake you up as the ship docks at some ports - but I think this is common with most cabins at least on that level. Also, on the final day, you will hear/feel those thrusters early and often as the ship needs to do a 180. Finally, right below our cabins is the freight doors, so you will hear some loading/unloading machinery early that last morning as well. Otherwise, the rooms are very quiet for other parts of the cruise.
With regards to cabin noise, we found out that lot of the rattle comes from things like the wooden closet hangers rattling up against each other -so if you address things like that, you can cut down on a lot of in-room rattling.