cabinets, stairs with flip up steps and very narrow stairs. Each step goes up one at a time for each foot. It is sort of spaced so you are putting one foot per step with a steeper step. Very space-saving.
Storage under stairs at Loon Lake for musical instruments (have plugs in the walls at the back of the closet, and have amps on wheels: just pull out and use, no setup). Since the stairs turn, even the lowest cupboards would be a couple feet high. That way, the musical instruments are out of sight, but easily available for an impromptu concert in the living room. There could even be shelves inside one door for music books.