We have ~the same number of cruises under our belts as you, but this will only be our 2nd Carnival Cruise - the first was the Carnival Pride in 2009. There were things we liked about that cruise (always being able to drive to port is a big plus, and much more so with so many major flight glitches the past couple of years), but there was a huge group of Baltimore Ravens fans onboard, and at times it felt we were at a really bad frat party. After years of Royal Caribbean, as much as I've enjoyed all the sailings, it's starting to feel like the 'same old' thing, and we're looking forward to so much that will be different and new to us on this ship.
That's wonderful about your niece's intro to cruising. I love seeing multi-generational family groups on cruises and miss out on that - we have some family members that are afraid they will be seasick and some that don't enjoy cruising or visiting the same warmer climates that we do, so we haven't been able to organize a family sailing.
'Welcome Aboard'!
We never get bored going to St Thomas and San Juan and are really looking forward to the 3 new ports for us - T&C, HMC, and Amber Cove.