For an overview of Penn Station, I highly recommend The Late, Great Pennsylvania Station
by Lorraine Diehl. (Hardbound: American Heritage Press, 1985; softbound: Four Walls Eight Windows, 1996.) Chapter 1 is about the effort to rescue Penn in the early '60s, and Chapter 15 is about how PRR came to the decision to tear it down. In between are pictures and descriptions of its construction and history.
On page 143 is a picture of the long, airport-like state of the art ticket counter installed in the waiting room in 1956. Not only did it block off direct access to the concourse (you had to walk around either end of the behemoth), but Ms. Diehl likens it to "an ugly saw-toothed clamshell". The book also has pictures of the glass-doored stores that were retrofitted into the corridors as PRR turned to Penn for revenue sources beginning in the '50s.
I would have liked to see Penn in all its Romanesque glory.
But I missed out on it. I only got to see the, er, transformed version of Penn, which I've caught subways from and to which I took AMTK from PHL in 1973.