Deciding which Carnival ship to choose and itinerary
I hope my comments are taken in an unkind context, but to me, it's always interesting how cruisers today are seemingly concerned about the size of the ship. As a lot of we old-timers know, the mega-ship phenomenon is something that really came into being in 1980 when the SS Norway steamed into Miami for the first time...and she was "only" 70,202 (or thereabouts) at the time (before the addition of the extra decks). Even then, the Norway absolutely dwarfed everything (with the exception of the QE2) in the industry.
I remember my first cruise in 1979 on my honeymoon on the Sunward II. She was only 14,000 tons, which was considered an average sized ship for the day. As a matter of fact, after the Sunward II, we cruised on the Skyward (16,000 tons), the Veracruz (10,000), Flavia (12,000 tons) and then on the "gargantuan" (or so it seemed) Mardi Gras at 27,250 tons.
In any event, I don't think I would let the size (or newness) of the ship dictate totally my decision on which to sail. I think I would be more concerned about the ship (or line's) past reputation for service and overall cruise experience. I would also reference my past personal experiences on how the line handled situations when things went bad (problems in the stateroom, dining room, etc.). Also, and maybe most importantly, the advice of a good travel agent can't be underestimated.