I think the sandy beach will definately be appealing to them, since Pop doesn't have a beach. The hammocks are fun too!
Also, the pool is a BIG highlight for young kids, likely even more so now with the refurbishment. The main area with the food court is fun too with fun calypso music playing & the CM's often have fun games & instruments.
I think your DD's will have a great time at CBR!!
Only thing I would like to warn you of is your choice of buildings. CBR is a huge resort &, while I personally do not mind the walk around the pond, your little ones might get tired after a long day & I would suggest either booking a preferred room (very close to the main hall) OR requesting the Jamaica buildings (which, IMO, are basically preferred without paying the extra fee). Keep in mind though, CBR offers internal buses and several bus stops within the resort, so you do have choices.
Have a great time-we love CBR!