There is quite a big age gap between my two youngest boys, nearly 7 years between them, thus, their tastes are very different; Lewis wants plain cream walls, whereas Jacob wants bright orange walls. So we compromised. We will keep it cream walls, bar the end wall on Jacob's side where we will paint it orange and it will become his feature wall.
Lewis's new double bed is arriving today, and we are ordering Jacob his cabin bed, with orange bedding and some wall-stickers of his choice to stick around his area of the bedroom. At Lewis's end of the bedroom is a bay-window, and my carpenter brother is building Lewis a fitted desk within the bay-area and Jacob would like a desk so he can put his TV and Xbox on.
So all being well, they will be fine for the next couple of years, then as Lewis approaches his mid-teen years, I have a feeling he may want his own space.
I shared a bedroom with my younger sister, it was quite a small bedroom, we had bunkbed, I was on top, she was on the bottom. While I can remember a few territorial squabbles, or me keeping her awake as I ground my teeth, or I pushing her on to her side as she was snoring - we get on fine now.
Designing a shared bedroom can be a challenge for many parents, especially when there is an age gap between the children - do you go for a open plan share environment or do you try to give each child their own bit of space, however it does depend on the size of the room which will dictate the approach you can take.