Enjoy this, on Lockheed Constellation! This is how a plane could and should be equipped!
http://www.mcguinnessonline.com/burt/images/paa9z.jpg
This is on a scheduled, ticketed airliner.
Note that while I cannot find actual images of two adults sharing this kind of bed, it has been tried and said to be perfectly comfortable.
DC-6 has beds, too:
http://www.ovi.ch/b377/articles/SuperLiners/
Looking down, the beds are 102 cm wide.
Already the DC-3 was designed as Douglas Sleeper Transport. The lower beds were 91 cm wide, the upper berths 76 cm.
Observe that while Boeing 377 or DC-6 or Constellation were called big at the time, their size is not all that impressive. DC-3 is smaller than CRJ.
Show a scheduled CRJ ticket for an 91 cm wide bed!
Constellation, DC-6, DC-7 and Boeing 377 were slightly bigger, but still small. Maximum of 5 seats abreast in Economy... about the width of DC-9, much smaller than Boeing 737.
The longhaul jets are wider. Even on the smallest widebody 767 there is a plenty of width for, say, two aisles and 4 90-cm-wide beds... 4 abreast, every seat with aisle access, is not uncommon on First Class, whether A340 or B777 or rear of B747 nosecone.
But the First Class seats are usually advertised as having 50...60 cm seat width.
Help! Where does the space go? Why cannot a modern plane have beds with 90...100+ cm mattress width comfortable for two?