A mix of literary and sociological references and perspicacious musings, ''America Day by Day'' brims with philosophical speculation and memorable aphorisms. After attending a Louis Armstrong concert at Carnegie Hall, Beauvoir writes, ''Americans have more or less murdered jazz, but they love it still.'' Traveling through the Mojave Desert for a hundred miles past curio shops and jackalope stands, she observes: ''Tourism in America is something privileged, it does not cut you off from the country it would show you. On the contrary, it is a means of access.'' And, at last, in a line that could serve as a motto for the whole Beat Generation ethic: ''All these people whose destiny is mass-produced are haunted by dreams of escape.''