Guest room- Create a nook like this by suspending curtain rods from the ceiling. Put a daybed to be the bed in a small bedroom. Closing curtains allows you privacy to maximize all space for lounge and storage- its ok to have chairs right up to the bed!
This is another example of a layout that would be easy to install in a studio apartment - a loft bed with stairs would be a cheaper and nicer space saving solution than buying a Murphy bed. Maybe even in a small bedroom.