6 aircraft and 7 cabin layouts, from the DHC Dash 8-400 to the 767-300ER. Pick one for its seat map, the best seats and the seats to avoid.
There are seat maps for 6 Icelandair aircraft here: the Airbus A321LR, the Boeing 737 MAX 8, the Boeing 737 MAX 9, the Boeing 757-200, the Boeing 767-300ER and the DHC Dash 8-400.
The Boeing 767-300ER, with 262 seats: 25 Saga Premium and 237 Economy in its main layout.
The Boeing 757-200, with 32" of seat pitch in Economy and seats 17" wide.