If I were going to opt for luxury cruise, I would chose to go all out, and enjoy a nice balcony cabin. Don't think an inside cabin on a luxury ship would give me the feeling of "luxury ship living".
I also don't think a suite on a Carnival or RCI ship is comparable in price to an inside on say Crystal. The comparison would probably be more like Crystal inside to Carnival/RCI balcony.. or perhaps Junior Suite.
I've cruised in several inside cabins, and I've cruised in Suites. Of course the "suite life" was most certainly nicer, but I wouldn't discount an inside cabin.... though I'd chose a balcony.
For me.. if a balcony wasn't possible, I'd just as soon go for the inside cabin, as I prefer the darkness to sleep in, if the other option is just a small window to look out.