M.M.
We have some friends that went with their kids to the Atlantis and they said it's not as great as all the hype you hear and see about it. I have not personally been, so cannot comment.
We have however taken a few cruises with our kids…they are 3 & 6 now and we are going again in August. LOVE it. There are sooo many activities for the kids to do. We have only sailed on Carnival with the kids, but I hear RC is awesome for them too. There are FREE kid camps on the boat that offer activities from 8:00am -10:00pm (after 10:00pm, they have babysitting that you can pay extra for). We would look at the daily schedule and pick out a couple fun things, like face painting, a scavenger hunt and making puppets and drop our kids off at those events. This gave us some adult time and the kids were off having a blast with other kids. All of the ships have pools and waterslides, but some have been refurbished or are brand new and have REALLY cool slides and splash pads now. Food is around the clock. Buffet style if you want casual or formal dining. Room Service is also free around the clock. Non-stop self serve ice cream is a HUGE hit too :) There are Casinos on the ships, bars, night clubs and shows such as karaoke, magic, talent and comedy. Each trip involves 1-2 formal nights where your family can get all dressed up for dinner. We use this opportunity to get a new family photo each year with one of the backdrops provided.
If you do a cruise, I would suggest getting a cabin with a Balcony. We got one for the 1st time 2 years ago and it was sooooo much better to have the door open and sit out there at night when the kids went to bed.
I could go on and on, but I won't…..