I listened to Jeff Buckley, Tori Amos, Chicane....just stuff I like. Anything that makes you happy is good, it doesn't have to be relaxation music.
For me I found having my music on calming and reassuring because it was so familiar to me. Other women find any noise incredibly distracting and can't stand it LOL. But I'd just recommend going with whatever music you normally like...better to have it and not want it, then to not have it and wish you did!