Don’t forget about VMS. For a long time VMS was a very popular operating system. It’s a lot like Apple in that it only ran on DEC machines. It was generally a bit more user friendly than unix, and also had a windowing system that was popular on later systems and is quite user friendly. For higher end machines VMS was still quite popular up until about the time NT 4 came out, which was when PCs finally started getting enough horsepower to compete. By the time win2k came out, users industry-wide had pretty much all shifted to using PCs. The death of the NT-Alpha project pretty much signalled the end of DEC as we used to know it.
The operating systems used on the old 8 bit computers, although archaic by our standards, were considered to be reasonably user friendly at the time.
And the design of NT owes a lot to VMS. One of its designers, David Cutler, went on to lead the Window NT design project, and there quite a few similarities in the architecture. Incedentally, take the letters VMS, move forward one step in the alphabet and you get WNT. Windows NT?
If possible, I would suggest a viewing of the PBS special Triumph of the Nerds: The Rise of Accidental Empires. Robert X. Cringely provides a fascinating look to help explain how Windows came to dominate the PC OS market, and leaves you with the impression that, at least for Bill Gates and Microsoft, it was more luck and serendipity than quality product and programming skill.
You can find information on the special, including a complete transcript, here.
There were also several DOS front ends, such as XTree and Xtree Gold and a horde of me-too competitors.
They had essentially the same look-and-feel as Windows’ Explorer in about the 95/98/NT incarnation: a two-pane display with a visual directory tree on the left and listing of the files in the selected directory (“folder”) on the right. You could copy, delete, move, rename, create or execute any file from that interface.
The early versions predated the mouse. Not exactly a GUI, but certainly a proto-gui. These things first came out almost immediately after DOS 2.0 added the major new feature called subdirectories and suddenly folks could get lost in the maze they’d created without a visual tool.
IIRC, in DOS 1.0 there was only a root directory per volume. When a volume only held 360K, that wasn’t quite the limitation it would be today. <g>