The stuff that works best for me is the Phillip Glass early crossover stuff (i.e. post-Einstein.) Things like Glasspieces, Dancepieces, 1000 Airplanes on the Roof, The Photographer, and the three *qatsi films. They're minimal enough not to intrude on the foreground, but also not as harsh and "difficult" as the early stuff like large chunks of Einstein (except the knee plays) and Music in 12 Parts.
Philip Glass symphonies Wagner's The Ring ( unless you speak German ) Slayer