Robert Leach's post reminds me of the early 80's when I worked for a company that insisted that its execs flly FC, and at that time DL was giving 2000 miles per FC leg (does anybody else remember those pink boarding passes?).
One typical four leg business trip thru the south would get you 8000 miles, altho I do not recall any special status from those early days of the Frequent Flyer program, such as Eastern's ET (Executive Traveler) designation.
The first that I recall seeing any notice of Medallion status was about in '85, after I had stopped using DL, a stop that lasted about 20 years.