Hi!
We are avid 'cruisers' and have been on numberous cruises on quiet a few cruise lines, including Disney. From the moment we boarded the Disney ship it was truly 'magical'. We've been on 3 Disney cruises now and even without kids I would choose Disney over any of the other mega ship lines. Here's why....
Most and foremost, the ships are smaller. I can get from one end of the ship to the other in 15 minutes or less. There are less people which makes it seem like there is a larger staff to passenger ratio (and maybe there is-or maybe it just seems that way-or maybe the staff is trained to make you feel like you are the ONLY people on board). Whatever it is, you will feel like a rockstar as soon as you step onboard.
Secondly, the format of the ships activities are so "kid" that it's almost not "kid" at all. I know that sounds wierd, but let me explain. The children's areas/activites are set up so that parents can feel comfortable dropping off their kids. Therefore, during the cruise, I saw mostly adults in the hallways and around the adult congregating areas. The kids were so busy doing 'kid' things in another part of the ship that parents have time to actually enjoy the cruise too.
And last, but certainly not least, is that there are teen areas/activities and adult only activities. The excursions are fantastic and diverse so there is something for everyone. That is certainly not all the things I loved about the Disney cruise but it's the top 3 reasons.
Now, as a con..... I think most people would agree with me on this ..... and that is Disney cruises are more expensive than other cruises. That's is my one and only con I can think of right now.
The mega ship cruise lines such as Royal Carribbean, Princess, Celebrity, Carnival etc. are all also fun too. I strongly encrouage you to check out the online forums or talk to a travel agent about the atmosphere of each line before choosing one. For example, Carnival is very much a party ship. Don't expect the royal treatment, quiet hallways or such. Think 'college drinking party' at sea. Royal Carribbean is more of an athletic type cruise, Princess typically has older passengers etc. Every line has a reputation. And from what I've seen, there's a reason for those reputations whether it's good or bad.
Ok, I think my post is quiet long enough. Maybe I've given you enough things to think about and consider. Have fun on your trip! Not all cruises are created equal. So with the proper investigation you should be able to find the perfect one for your family!!