As for Aaron Copland, I am partial -- I would be, with my training -- to his settings of Emily Dickinson for voice and piano. Easy, mostly, on the ear; really bleeping difficult to sing, even the mighty Phyllis Curtin (recently deceased) was afraid of what they would do to her voice.

Although it isn't my favorite from the Dickinson cycle, some people, like composer Ned Rorem, adore Copland's setting of:

The world feels dusty when we stop to die
We want the dew then honors taste dry
Flags vex a dying face but the least fan
Stirred by a friend's hand cools like the rain

Mine be the ministry when thy thirst comes
Dews of thyself to fetch and holy balms