Most kids love to decorate their room. Let your small ones be part of the process, so they really can feel that it is their room.
If you are aware of your child’s fear of the monsters under the bed, perhaps get a bed with storage draws under it, meaning that no scary monsters can hide there. :0)
Kids love bunk-beds, even if they will only use one of the beds, they might have a friend over on a sleepover.