I looked at this thread and thought "Cool! I have an old Merlin Boeing 40 kit!" Single-engine biplane airliner with the four passengers inside and the pilot in an open cockpit above and behind the cabin. Then I found there's a beautiful resin kit available, also in 1/72 scale. Then I saw a resin Boeing 80 - biplane trimotor airliner. Then I saw that there's a resin kit of the Boeing 200, the Monomail. Like the Model 40, passengers inside, pilot on top, but all metal and a monoplane.
Then I thought, "Why spend the money when you already have the Merlin kit?"
But, but...the resin kits are so much nicer. Indecision is going to be the death of me yet.
I do have some old grainy pictures of the 299 (prototype B-17) I built for the Hill AFB museum back in 1990.