I worked at Lafayette Radio, TEch Hifi and Radio Shack at various points in my early years.
Here are teh recordings that I found most successful in selling systems back then:
1) JEff Wayne's "War of the Worlds". Most successful demo record overall. I used this on a system in front of the Radio Shack mall store playing into the mall area on the best system I could set up there and it attracted customers like flies.
2) Kraftwerk's "The Man Machine" also a big customer attraction
3) At TEch Hifi, we got the most mileage out of Steely Dan's Aja and Pink FLoyd's "The Wall".
4) At Lafayette, I used Spinozza by David Spinozza, Eric Clapton's Slowhand, Misfits by The Kinks, Grease and Saturday Night Fever soundtracks, and Octave by The Moody BLues to good effect.