Pack it all against one wall and the room becomes an arena for playing games, visiting with friends, or having an indoor camp out. Use a simple bunk bed as a starting point and create a cubbyhole for a sofa and book case on the lower level.
two twin beds. A curtain hung from that cute heading would disguise your "bedroom" if you chose. A curtain would work above as well for either a bed or built in shelves and hanging space for your clothing; I really love the idea of deep, built-in beds