We started doing that when our kids were 12 & 15. They were very experienced cruisers. For our Alaskan cruise, it was actually cheaper than putting all 4 of us in one room with verandah. Back then, an OBB included OBC from
DCL and it was tiered according to
Castaway Club level. We were platinum so each room got $350 from DCL and $200 from our TA. Having 2 rooms made that doubly sweet.
We booked one of us in each room and one child in each room. We asked GS for blank keys for all 4 of us so regardless of which room we're booked into, we could all go into our booked room or the other one.
It was so nice to have 2 closets, 2 bathrooms, and 2 TVs, not to mention double the space and privacy for me and dh.
The only hiccup I can recall was that every night I would tell them to turn the lock on the door. I felt better knowing no one could enter their room. That cuts both ways because on some mornings when we had early excursions and needed them to wake up by 6am, I couldn't get in there either. I think I just called into the room but I have to admit I was a bit worried that they would sleep through the phone ringing and we'd be late to our excursion.
It worked out so well, we did it again for our Mediterranean cruise the next year.
When they were 19 and 22, we cruised to Norway and they were offering VGT rates that were very enticing. That was the only time we splurged for 2 balconies. We had connecting rooms and asked them open the door between verandahs and that was a delicious amount of space. I would highly recommend that if you can swing it.