Good question, hucc. We have two adjoining cabins for our July AOS cruise, one for the kids and one for us, and I was wondering the same thing. It was a hard decision to make, as we usually cruise in suites, but thought we'd give this arrangement a try. I think we'll like having two bathrooms and separate bedrooms with "real" beds instead of a sofa bed. I think it works out really well for families.
The Grand's Family Suites look like a neat arrangement also. I don't know much about them except that they are aren't in the best locations. I don't like the way they are stuck in the very stern of the ship. I think the location may have been changed for some of them on the Golden. They usually sell out quickly, so book far in advance. BTW - I don't remember seeing any adjoining cabins on the Grand at all. RCI seems to be one line that has this feature and possibly Carnival.
Let's hope someone has pictures!