The first bookstore I ever worked in was very old-school in a lot of ways. Although the owner wore baggy old jeans and a torn tee shirt, had hair down to his waistline and was bushily bearded, he would stand for nothing other than classical music as the soundtrack of his rare book shop. Of course, "rare" is stretching it a bit. Like most used & rare bookstores, he had his share of old paperbacks, outdated diet books, and other 20th century detritus (in fact, he taught me as much what NOT to stock as otherwise). Oh, but he did strive towards his own vision of what an antiquarian bookstore should be.
This vision included a certain odd snobbery in the realm of music. My boss would tolerate nothing other than Mozart, Bach, Purcell, and other established masters of polite strains and stately processionals. Rowdy sorts like Mahler and Stravinsky were not welcome, although occasionally Beethoven was given a chance during particularly slow periods. I'm not sure whether my boss actually preferred this music personally, or just thought it was more conducive to browsing by the book-buying public (which, in this case, actually consisted more of punkish students than the highbrow, monocle-wearing types my boss longed for).
My second boss mostly adhered to the same policy of classical music only. He relented a bit, though, on the weekends, when he was known to allow Broadway show tunes and even folk music. Still, we did have to maintain a certain decorum in our choices. Joan Baez, yes; Phil Ochs, never.
I've always told people that one of the main reasons I wanted my own bookshop after many years of working for others is the ability to choose my own music. Of course, officially the music is just for my ears anyway because of right-of-use issues. But I can't help it if the music wafts from my office into the adjoining book rooms, can I? Anyway, in my own shop I cut loose with a vengeance, playing everything from rhythm 'n' blues to the Bonzo Dog Band and Cab Calloway. We have actually had people dancing the Lindy in the aisles and have been told more than once by toe-tapping customers that we play the best music they've ever heard in any kind of bookstore, rare & rarefied or not.
And, strange as it may seem, we even like to play classical music from time to time.