Assembly comprising a plurality of blocks aligned behind one another, in one and the same direction and substantially along one and the same axis, each block comprising at least two adjoining seats which can be individually converted, by a relative movement of elements (31, 32, 33) of each of the said at least two adjoining seats, between a chair configuration in which an occupant of a seat in question is in a seated position, and a bed configuration in which elements of the seat in question form a bed plane and in which an occupant of the seat in question is stretched out substantially flat and substantially horizontally, the at least two adjoining seats of a block being arranged side by side and oriented substantially in one and the same direction, in which assembly: • a block comprises in a rear part a separation space situated substantially between seat backs of the at least two seats of the said block when the said at least two seats are in the chair configuration, and open towards the rear of the said block so as to determine a foot area associated with each of the at least two adjoining seats of the block situated behind the block in question in the row of aligned blocks, the said foot region being situated in the extension of the bed plane of the said seats of the said block situated behind the block in question; • a longitudinal axis of each of the at least two adjoining seats of a block, in the bed configuration, converges towards a convergence point situated in a vertical plane of symmetry of an assembly formed by the said at least two adjoining seats and in front of the said seats; and characterized in that: • the foot regions associated with each of the at least two adjoining seats of the block situated behind the block comprising the separation space determining the said foot regions are superposed, at least in part, in a vertical projection; • when the at least two seats of a block are in the bed configuration, the bed plane of one of the said at least two seats is situated at a height which is different from the bed plane of the other of the said at least two seats. • a block comprises in a rear part a separation space situated substantially between seat backs of the at least two seats of the said block when the said at least two seats are in the chair configuration, and open towards the rear of the said block so as to determine a foot area associated with each of the at least two adjoining seats of the block situated behind the block in question in the row of aligned blocks, the said foot region being situated in the extension of the bed plane of the said seats of the said block situated behind the block in question; • a longitudinal axis of each of the at least two adjoining seats of a block, in the bed configuration, converges towards a convergence point situated in a vertical plane of symmetry of an assembly formed by the said at least two adjoining seats and in front of the said seats; • the foot regions associated with each of the at least two adjoining seats of the block situated behind the block comprising the separation space determining the said foot regions are superposed, at least in part, in a vertical projection; • when the at least two seats of a block are in the bed configuration, the bed plane of one of the said at least two seats is situated at a height which is different from the bed plane of the other of the said at least two seats.