Watch the clear height
Most NCR flats have a slab at 9 ft 6 in to 10 ft. A drop of 6 to 12 in still leaves about 9 ft of clear height, which feels comfortable. Below 8 ft 6 in a room starts to feel low, so in such rooms use a peripheral cove or island design and leave the centre at slab level, especially where a fan hangs.