I have seen mentions here and there on FlyerTalk about people choosing one scheduled flight over another in order to fly on a newer or better aircraft.

When I book a flight, if anything is noted on my itinerary it is typically just the aircraft in general: "767" or "777", etc.

SeatGuru shows a variety of possible aircraft (e.g., " 777-200ER Vers. 2 (773)") for given airlines, but is there a way of knowing exactly which aircraft my flight will use?