I am starting to learn a few things about cabin choices too.
There is a joke among cruisers - "the more you pay, the more you sway" in that higher up cabins which is often where the pricier suites are located feel the most tippy. If this might be a problem, one would want a lower floor cabin.
Middle of the ship seems to feel the most stable with more motion and wave action up front and more engine vibration towards the rear.
Agree, do be careful about what is above and below you if you have a choice. And up front also has reports of noise problems when the anchors get dropped early in the morning on port arrivals which often happen well before you are allowed to disembark.
Other features depending on the ship are clear plexiglass balcony railings or solid metal ones. Irregular shaped rooms near the curve of the ship. Tubs or only showers can show up in different room choices too at different price levels. Some double rooms have fixed twin beds that cannot be moved and some have twin beds that can be converted to a full sized double.
Some put the seating towards the window or balcony and some put the seating near the entry door. Some have large closets and ample storage, some have little. Some have good electrical outlets and others are stingy about plug-in items.
Verandahs can be large, enclosed and private on some lines like HAL, or tacky little stick on affairs on some of the larger mass market lines where you barely have a chair and tiny table and they are exposed to the elements and all other passengers.
They are best when you have a lot of viewing to do like the Panama canal, in warm weather when you can enjoy being outside in the breeze, and when there is shoreline scenery to enjoy like in Alaska as long as you are on the right side to see things.
They are nice particularly even when the above does not apply for having the floor to ceiling window and the sense of light and space. They are wonderful for room service breakfasts particularly when coming into port to see all the dock activity (again hoping you are on the "right" side).
I think it is better to choose a good moderate cost line like HAL with a balcony rather than a luxury line without one like Crystal for similar prices. Even better to choose two HAL with balconies over a single cruise with Crystal without. That is a choice to make when stretching the travel dollar - a better suite on a lower priced line or a low-end cabin on a higher priced one.
The longer the cruise, I think the more important the cabin is for down time. If it is a shorter, port intensive cruise, then a cabin may be nothing more than a place to sleep and shower.
Having a window can matter if you like to wake with the sun. Never found a line that has a fake "sunrise" on a timer as your wake-up alarm in the inside cabins but would love to find if they exist. It is good advice to take the cheapest inside cabin if this can make or break taking a cruise or not. But if you can spring for at least a port hole it will make things better.
Being on the promenade deck can be a problem if you have windows because people can look in as well as you being able to look out. Plus there is a lot of foot traffic going by all the time for noise and nuisance. One cruiser found the inside cabin on the promenade deck was her favorite because the world was just outside her door.
Being somewhere in the middle of the ship in both floor level and section of the ship to me is best because I like to take the stairs to my ship board activities. Usually the dining is on the lower floors and the buffet and pool and observation decks are on the top.
So if you want to avoid the elevators and those crowds being in the middle means you only have to go up and down a few floors to get most anywhere (except on the really huge ships which do force you into either daily marathons or those darn elevators.)