Although this topic is not HAL specific, I'm a HAL fan so here I'll post.
I've seen quite a few postings on cabin locations. I've had cabins in the fore, the middle, and the aft of the ship. I've been on decks three, six, and right below the Lido kitchen. I've never been on the lowest passenger deck, lucky me.
To me, the most important thing is a quiet room. Having ten years of military expereince, I've slept in some pretty lousy conditions. Evenutally you get used to the noise, but it wears on you. Every ship has boom boom cabins (cabins over some big peice of reciprocating machinery). A cruise ship is a massive thing that has some massive power generation equipment on board. usually this equipment is below the lowest passenger deck. I avoid the lowest passenger deck because of this. Study the deck plans. If you like quiet, avoid being close to elevators, they go ding throughout the night. Also below public bathrooms and high traffic areas. When I was below the Lido kitchen, I could hear heavy foot traffic and carts for short periods just before and after meals. It wasn't bad. Being below a self serve laundry can also be bad. Once I was above the theater; forget sleeping during show hours, but it's still better than a boom boom cabin.
If you don't like rocking fore and aft, then a mid ship room is the best. An aft cabin isn't bad, but a forward cabin is the worst. If you can't handle side to side rocking, get a room on land. I personally like the rocking. It's peaceful and part of the experience of being at sea.
If you want to be close to everything, you won't be. No cabin is close to everything. The question is how close are you to the elevators or stairwells. On a HAL ship, I prefer to be near the aft elevators. My preferred locals are the aft pool, the Lido buffet, the dining room, and outside on the promenade deck. I go to these areas at least once a day. IF you like the midship areas, then try to be near the midship elevators and so forth for the forward areas.
I'd be interested to read the points of view of others.