Great idea RE the twin mattresses. I also love the tree pictures on the wall! Love to display kid-made art in a kids room! Two twin mattresses, some plywood, and a great playroom that doubles as a guest room or sleepover room.
CJWHO ™ (House G by Maxwan Architects + Urbanists) - Love open concept, and if you must have stairs, they should be open, as well! I love the idea of all the book shelves along the stairs.great use of space!