The 2 oldest girls are together. My youngest 2, a boy and a girl, split the other one.
Once I finish the basement the 2 oldest are going downstairs and will have their own rooms - but we will see how long that lasts for. I get the feeling that they will want to sleep in the same room and make the other one their study/play room.
My youngest 2 will then each have their own room - which makes sense for a boy and girl.
I didn't have my own room until I was 12 when my youngest brother was able to be in a room with my other brother. Some things I liked about it, other things I didn't. But we never really stayed in our rooms anyway we were always in our large family room so I dont' know how much of a difference it really made.