bed, counter for beds, floor, padding, tatami
床 centers on a flat surface for resting or placing things: a bed, floor, or tatami mat. The padding and counter senses extend naturally from that idea of a supportive layer.
床 combines 广 (building) with 木 (tree/wood), originally referring to a wooden platform or raised floor inside a building. Over time it extended to beds and tatami.
Under a roof 广, a wooden 木 platform becomes a bed or floor. Picture a simple wooden bed frame inside a room.
For ショウ, imagine a showroom with a wooden bed on display: show -> ショウ, and the bed is the centerpiece.
floor
bed; bedding
clinical (e.g. pathology, training, trial)
rising (from one's bed); getting up; getting out of bed
under the floor
barbershop; barber shop; barber
bed; berth; crib; cot; bedroom
sickbed; (hospital) bed
hotbed; breeding ground
alcove slab; wooden board placed in a tokonoma; baseboard; base plate
floorboard
on a floor; above floor level
thalamus
tokonoma; alcove where art or flowers are displayed
riverbed
raised-floor (truck, etc.)
raised-floor (building)
seedbed; nursery; seed-plot
mineral deposit; ore deposit
bedsore