Here's a tidbit that maybe all members know about the DC-4. In Alaska a fuel delivery service still flies them, as well as the C-46, called the Curtiss Commando, quite a performer back when they were flying them over the "hump" on supply runs.
I think the name of the service might be Nenana Fuel, they have huge onboard tanks for delivering fuel supplies to remote Alaska locations. I think it's remarkable that an aircraft that old, can still be doing rough duties like that. Rugged buggers they are.
Even the modern jets don't hang around that long, about 30 years and 60,000 flight hours will make them candidates for the scrap heap. But they are a different sort, the complexity of the systems renders them not cost effective for major rebuild, best to make soup cans from them and just buy new airplanes.
And to me, the DC-4-6-7 propeller driven airliners just "looked right."
Patrick