House in a Box: Move fireplace to livingroom/porch corner and make a passthrough fireplace. No up stairs - just tall ceilings with windows for light. Wrap porch all the way around to bedroom and add french doors.
Guest house for the cabin this is just under 500 square feet but the layout is really efficient. shows what can be done with minimal square footage. Add a covered porch, a finished shed for an office and a storage shed -- have a pretty cool set-up