Having been on 2 different cruiselines,(platinum cruiser with
DCL) trying a third as a trade off with friends of ours, I have yet to see any ship that is confining or claustrophobic.
There's advantages and disadvantages to every cabin class on every ship.
Lower cabins less movement, typically closer to debark points on the ship to get off and explore
Bad points- limited view through portholes, (think distance or looking at the pier as opposed to over it) can sometimes hear/ feel thrusters moving the ship or supplies being loaded etc.
Upper cabins better views, closer to pools, food entertainment etc. Typically larger sq footage wise also.
Bad points - you'll feel more movement. This is usually when the seas are higher then normal.
Don't get me wrong. Everyone loves their cabin selection for different reasons. We typically will sail a balcony cabin usually midships with a deck or 2 buffer above and below public spaces. There is nothing like sitting on a balcony relaxing watching the sea pass, with a drink in your hand, or looking at the stars at night.
Weve sailed 4000 pax ships at capacity and you'd never know that there was 3999 other people onboard with you. The ships are large and laid out and timed so not everyone is in the same place at the same time. Except for deck parties which are different stories. Theres tons of things to do on any ship like ice carving demos, classes like wine tastings, movies, tours, just about anything you can think of.
The best thing I can suggest besides doing what is already being done( asking questions) is approach cruising with an open mind. Read the cruise summaries that people post, look at a shorter cruise to see if cruising is for you.( its not for all), join the Facebook page for your cruise or the cruise meet page for your cruise, after that relax and have fun.