On the Dream/Fantasy, a category 8 is cheaper than 2 inside staterooms, but you need to book them early, because there are less than 20 or so that fit five.
On the Magic/Wonder it is cheaper to get two inside staterooms than to get one balcony (they do not have anything below a cat 4 that sleeps 5 or whatever their lowest balcony is...they keep changing category numbers so it gets confusing).
We have five and prefer the one room...for me less to clean up! Plus, we enjoy being together as a family and talking during the night as we're going to sleep...if you're in different rooms you lose some of the family time that we like to have. We've done it both ways and prefer one room.
It also is a plus for us to have a window, I would prefer the seat window on the cat 8 over a balcony...hth!