Tons of stuff that I like is "soft" music . . . it's kind of difficult to say what would be the "softest"--that designation could describe so much different stuff. Is Brian Eno's Music for Airports "softer" than Doris Day's "Autumn Leaves"? Is Oregon's "Moon and Mind" softer than Daniel Lentz' O-Ke-Wa? Those are just a few of my favorite pieces of music that might be "soft." But that's not even the tip of the iceberg, and it's not even to mention soft rock/yacht rock.