I love the idea of building the bed into the structure of the room for children's rooms. Beds are large pieces of furniture and take up space. This allows for more floor space. I would make the bed into a bunk bed for both Laura and Hannah!
If your bedroom is on the small side, consider investing in a cabin bed. It zones the (limited) space and the raised section can incorporate lots of storage, too. Trick the eye into seeing a library of books rather than plain wardrobe doors.