How do you think kid’s room? Should be wonderful and colorful? I think it's little difficult to design a kid’s room. Because 3 elements should be included.
1. Keep the room bright. So white color can be the main color to light up the whole area.
2. Keep the room spacious. Because if the room is cramped, it`s bad for the mood of children, maybe they feel depressed. How to do this? If in limited space, avoid to make too many cabinets around bed. If in the large space, it`s better to make partitions clear, such as reading area, sleeping area, dressing area.
In the small walk-in closet, we can settle some functional accessories to improve user experience. Maybe on the upper level of hanging area, we can settle a pull-down rod.
3. Add other appropriate color. Different colors has different effects on different people. So according to the personality of your children, you can choose other color with low saturation, which looks soft. For example, the blue above is helpful to let your children calm down.