We just stayed in a 2Br (H4) suite in the Haven on Epic. We also have a family of 5, but with teens and young adults. Space was fine - oldest slept on the LR couch. Storage for the second bedroom was a little tighter, but tons of space in the master. I'm still not quite sure why they give you a swanky bedroom with mood lights and no lock on the door... 🙂 I agree with Two Wheels that it's important to know what the butler /concierge can do for you to best benefit from the experience. They have a handy phone that you can use to call the butler (which I never did), but it was the last day before I realized I could also carry it around for the kids to find US (a feature that had some technical guffaw the day we finally tried it).
Our cruise happened to be THE spring break booze cruise so avoiding the chaos of 4000 drunk college students from the relative peace and calm of the Haven was amazing. The restaurant was great for breakfast (a nice buffet of grab and go items and/or full service options) and dinner, but for some reason all the food ordered at lunch was so-so with fries and other hot food not served hot. The priority embarkation and disembarkation (for GSC too) was also awesome, but sometimes it was hard to follow the special instructions for Haven guests amongst the regular announcements and dailies.
We have cruised Royal 3 times (in two rooms, and once in a Oceanview family suite) and Disney when we only had the one kid. I thought I wanted something different but I was not a fan of this experience and I don't know if the premium I paid was worth it. Being used to a full production show each night in the main theater, I was disappointed with the entertainment onboard. Priscilla was fun, but it and Burn the Floor were repeated over the week instead of a show each night. Howl at the moon was in a venue set up like a seminar, with rows of seating hard to get around. Some of the game shows were fun, but they were held in the atrium where it was hard to see or hard to avoid. Cool bars but again in public traffic spaces or by elevator banks that made it hard to visit and connect with fellow shipmates. Escape the Big top was fun and well done.
My teens enjoyed the teen area and activities. We avoided the pool deck due to the aforementioned college revelers. Now some people say the Epic is a unique boat and isn't necessarily representative of NCL. Maybe so, but it just felt different, maybe less "happy" than Royal. I spoke to other first-time NCL cruisers who felt the same way. This ship's staff was seriously lacking in enthusiasm and even in general knowledge about ship amenities and policies. Drinks were well-made but lines took forever. Food was okay, but unlike the grab and go Sorrento's on Royal, you must check in and be seated at O'Sheehan's and then you cannot bring your food out (even to the counter overlooking the atrium). Found that odd. I both liked and didn't the freestyle dress code. All of us were glad to not have to change for dinner (especially the boys who would have had to wear, oh the horror, some pants). That said, shirtless and bikini clad people parading through public spaces all day was awkward. With the gratuity charges and exclusions, the freebies didn't really feel free. Make sure to check out the amenities on your boat and be sure they work for you. Our boat had a 18-plus sundeck but families with older kids were regularly up there and no one seemed to complain. Not sure if that is helpful to you, but it was our experience.