If you like Disney at all, 7 nights isn't at all like being trapped in a Chuck E Cheese. Disney is a true premium brand like Holland America, while NCL is firmly a mainstream line. While Disney is ever-present, the adult areas and options keep it tasteful. It's a great family experience. They know when enough is enough. I have many adult clients without kids who go on and absolutely love it. Service levels are fabulous.

Don't be afraid of having your kids in the program. Just listen to them if they're having a great time. Do be prepared that they may actually prefer time in the program than with you - if so, take advantage of your own vacation time with your spouse

There is no dressing up on NCL at all - while there is one "optional" dressy night in one of the main dining rooms, everything else is resort casual. MUCH different experience than a HAL cruise. It's more like an all-inclusive resort vs. a traditional cruise. And that's on purpose.

By the way, I think you're over-estimating the price of air to FL. Look at Jet Blue out of Boston to Ft. Lauderdale (which would get you either FLL or MIA cruises easily). Usually much lower than $400/person round-trip. Can't under-estimate the hassle factor of flying with family, but you might be surprised by the savings.

I totally agree that NCL has the best suites at sea of the major (non-luxury) brands. Totally different experience in there, especially in their newer ships. Spirit doesn't have all the same amenities, but still makes navigating reservations in the specialty restaurants and everything else much easier.