Hidden doors -- This company makes cabinets, bookshelves and anything you can think of that fits your existing doorjambs thus hiding the door (and also making use of the space). If you click through checkout the gun cabinet door. Lots of great ideas.
++pic only A great tiny house solution for single level bedroom. Murphy Bed and sofa in one. Add an ottoman with storage for a foot rest during the day filled with your pillows for the bed - Montana Murphy Beds