With every cruise we've been on, we've booked a "slightly better" room each time... perhaps feeling the experience would be ever better as a result! For the most part, it's worked out to be true... until this last cruise, which made us believe there's a point of being just "too much".
There's a long list of "suite" accommodations on many ships these days, especially the more "massive" ones (like the Allure). We've now been in at least 6 of these classed rooms, starting out with the "Junior Suite" several years back, and elevating most recently the "Owner's Suite" on the Allure.
I'm not sure just how other lines (other than RCI) compare, but can tell you that all you're really getting with such a room... is indeed, "room". The furnishings are of the EXACT same type/quality as an interior stateroom, or found in virtually any public area. The deck was painted to look like teak, and indeed much larger... but again, just more room. It's true that with so many others on board, "space" is a TOTAL premium... but if it's "luxury" you think you'll get beyond that, you'll simply not find it by paying 8-9 times as much as many people on board are.
All in all, I'd have to say that by doing a Junior Suite (which gets you a minimal amount of "special treatment") is the best "deal" on RCI... though if you want to get into any special lounges or show seating, then you'll have to bump up one cat from there. Doing the OS was a major disappointment for us, a bad decision that really made the cruise rather unnecessarily expensive... and not very gratifying, after blowing so much hard-earned money on.
It should also be noted that virtually all crewmen on this ship seemed to be more absorbed by "when they got off" than being conversationally pleasant... I'd never seen that before, on any cruise.