Go to a local library and check out some recordings, or listen to them there, if facilities permit. Your daughter will probably latch onto some favorites pretty quickly. I suggested the Bandenburg Concertos because Bach's work in this series is cohesive. Once you're familiar with the basic themes, you can let the music slide into the background, and when you're listening to a particularly nice passage, you can engage, and then let it fall into the background again. I would advise against any type of "elevator music" that you can automatically dismiss as "background" - children need to be engaged. The book "Goedel, Escher, and Bach" was a bit too holistic for me, but some of it was spot-on. There is structure, organization, and thematic cohesiveness in Bach's work (especially the Brandenburg Concertos, IMO) that transcend "mere" music (if there is any such thing) and provide a backdrop for pattern-recognition, problem-solving, etc. When I was doing homework or studying Chemical Engineering in the early 70's, I often had this music on the stereo, despite the fact that I played blues and rock at frat parties every weekend.