Excellent stuff,
Seat 2A. A few recollections:
Seat assignment was done at the gate. There was a chart of the airplane seats, with each seat represented by a sticky-thing with the seat number. If you wanted 12C, the gate agent removed the 12C sticky from the chart and pasted it onto your boarding card.
There was no security as we know it today: No metal detectors or carry-on X-Ray--just get on the plane and go.
The Eastern shuttle between New York and Boston or Washington was unique: there were no reservations, and you could buy your ticket on the plane. Instead of a beverage or meal cart, the stewardesses or stewards would come down the aisle and collect your fare.
The most significant difference, for these readers at least, between then (70s) and now: No frequent flyer programs in the 70s!!!