This instrumental piece, Thaïs (2), from This Mortal Coil's Filigree & Shadow spent a good deal of time on repeat during my second year at Very Expensive University located in a not-very-nice part of Los Angeles. The first half of that year was both tumultuous and miserable, and ambient music calmed my mind. The distant helicopter sound on the track echoed the actual helicopters that frequently circled overhead. The synergy of my environment with the record negated reality's menace.
The rest of the album is haunting, melancholy, jarring and wistful by turns, with sparse vocals. I find it comforting.
[This Mortal Coil's "Thaïs (2)", YouTube video, 03:14]
ETA: I simply must mention Ivy and Neet from the same album. It's a slow, simple piece dominated by a few piano chords that I kept on repeat after my grandfather died.