We will be trying RCCL's Voyager in October. But have been on Carnival Pride & Norwegian Dawn as well. Of the two Norwegian was much better for the kids. My son is 5 & my Daughter is 1. There is nothing for kids under 2. Your kids would both be in the same section of the kids club on NCL which is great, with a ball pit & large open play areas. There is also an excellent kids pool play area behind the club with two slides & a wading pool, very fun!! Ther is a separate section of the buffet that is "kid size" that my son just LOVED!! The itinerary is not SO bad. It is from NY to NY with stops in Port Canaveral (most go to Orlando for the day), Miami, Nassau & Great Stirrup Cay.
I have always heard that the Voyager class is the closest you will get to Disney without going Disney!! So we will be trying it next year.