The sleeping arrangement of the kids allows my oldest to sleep with someone else because she's scared of the dark. The twins don't like sleeping apart from each other. After all, they were together before they were born. In fact, they have always wanted to sleep where they can put their hand out and know the other one is there. When they were babies we had to put them in separate cribs because they would roll around and wake each other up and the only to get them to calm down and go the eff to sleep was if I put their cribs right smack together so they could see each other without one waking the other by bumping into one another. Once everyone was old enough, we put two Ikea little kids' twin size loft beds in the kids' bedroom. This way one is in the loft position and has a tent cover and a twin mattress underneath so it's effectively used as a bunk bed. The other is flipped over so it's a twin bed with a canopy.
The twins -always- sleep in the same bed. The third bed is never used except for a quiet place and reading space. The play room and the rest of the house is for being rowdy but the 2 actual bedrooms are quiet spaces. Even friends are not allowed in bedrooms, nor do the kids want to let their friends play in their bedroom most of the time these days. I also don't want the pets in their room when they're not in there, so I put up a baby gate. It's one of those gates that that you have to step on a pedal while simultaneously pushing the door with a little force to open. So, the twins have figured out how to open it if they stand on the pedal together while one of them pushes the gate with both hands so the gate can stay latched so the pets don't shove their way in. Killer noticed their joint efforts and has taught them to yell "Wonder Twins Activate!" when they do this. They have started to do this anytime they're getting into something together. It's super handy because now I know what they're doing when I'm not there to see them doing it.
May the Peace be with You.