My family (Myself, DW, and 3 kids 13B,10B,8G) all went on our first cruise on RCL Liberty of the Seas in April '08 on a 7 day Western Caribbean.
We will be taking a 4 day Disney Cruise in March '09.
The reason we chose RCL is that all my children are active kids involved with sports. We were worried that DCL would not interest my older boys, so we chose the Freedom ship.
In my opinion, the kids program on RCL was not that spectacular.
My 13 year old son went to the teen program the first couple days and did a couple things with the program (soccer in the basketball court and teen nights on the FlowRider). He told us most of the time they just hung around and talked. A couple activites that he likes (Guitar hero and video game night) were cancelled. He ended up playing in the arcade with his younger brother.
My 10 year old son was also fine with the kids program for the first couple days and then said it got to be very repetitive for him. Played in the arcade with his brother.
They both did mini-golf and the climbing wall a couple of times and enjoyed the FlowRider when open. (3 rides in 2 hours of waiting due to lines).
I ended up with a $200.00 bill for the arcade on debarkation.
My 8 year old daughter made a couple of girl friends and enjoyed the kids program.
We're going with some out of state family on DCL in March so they kids will have some cousins to hang out with on the Disney cruise.
Will let you know how that goes.