Most achingly-beautiful music

JOhn Barry's soundtrack for "somewhere in time".

Domenico Zipoli, Elevazione for oboe, cello and strings. Ethereal music written in the early 18th century. Zipoli was a Jesuit missionary in Argentina. Ennio Morricone's score for the film "The Mission" (also beautiful) sounds thematically very similar. Coincidence?

debussy and ravel.

Some of my favorites:

The Lark Ascending, Ralph Vaughan Williams
Cité de la Musique, Dino Saluzzi
Romance in F Minor, Dvorak
I Loves You Porgy, Keith Jarrett (solo)
A State of Wonder - the whole album, especially Gould's more recent take (Gould/Bach)
The First Time Ever I Saw Your Face - Roberta Flack
Cavatina – John Williams
Claire de Lune – Debussy
Como un fiore – Ludovico Einaudi (pretty much the whole Una Mattina album, which is exquisite)
Le Mystère des Voix Bulgares - Messetschinko lio Greilivko

So many more, but that's a start...