Cadet Chuck
I don't see the the point in making seats for an airliner. They couldn't be seen, once you close up the fuselage.
Depends on the subject and the scale. I am doing a Beech D-18 in 1:48 right now. Big windows, seats are quite visible, but at least kit furnishes seats. In 1:72 it depends on the subject. If the kit includes transparencies and the windows are big, I like to put something in there, though my scratch seats are pretty simple. I use styrene angle stock, cut seat rows, and mount on rectangular stock bases.
I would like to see more of a selection of aftermarket seats.
I recently built the airliner version of the Ju-52 from Eduard and bought their PE accessory package which includes cockpit and cabin seats. They were beautiful! Hard to see, but those little hard to see details add a lot.