Sleeping loft
A loft built high enough to sleep on, lifting the bed out of the room and freeing the whole floor below for daytime life. The highest-value vertical move — but it needs real height (~3.2 m+ total) for standing room below and sit-up room above.
Bed up, whole floor freed
The exception to the 'height is for rarely-used things' rule: you use it nightly, but it works because sleep is a once-a-day trip. Engineer it for the load, add an edge rail, and vent the heat that rises to the top.