There's so many pieces that come to mind when I think of the most beautiful....

But here's some of my all time favorites:
Elsa's - Richard Wagner
With Quiet Courage - Larry Daehn
Make Our Garden Grow - Bernstein

And probably my favorite: Elegy for a Young American by Ronald Lo Presti

Now, if we're also talking about orchestral music...I could go on for days

Edit: forgot to add
Russian Christmas Music by Alfred Reed
as wel as his rendition of Greensleves