5 aircraft and 5 cabin layouts, from the DHC Dash 8-400 to the 777-300ER. Pick one for its seat map, the best seats and the seats to avoid.
There are seat maps for 5 Biman Bangladesh Airlines aircraft here: the Boeing 737-800, the Boeing 777-300ER, the Boeing 787-8, the Boeing 787-9 and the DHC Dash 8-400.
The Boeing 777-300ER, with 416 seats: 35 Business and 381 Economy in its main layout.
The Boeing 787-9 has Premium Economy in at least one layout.