People have claimed that sleeping berths vanished with propliners because jetliners were too fast to need them. However, see Panagra DC-8:
http://dc8cockpit.catisp.com/panagra.htm

So, here you are. A jetliner with upper sleeping berths!

How do the Panagra upper berths look like when in use? And how do they feel like?

Do any other airlines have upper berths on DC-8 or 707 services?