Beethoven quartet opus 135, especially the third movement. Several others, about an album or two worth of music. Ravel’s quartet is up there. I melt when I hear George Duke’s rhodes solo on Blessed Relief (a great piece overall). Stuff like that.
Barber's Adagio for strings, although it gets referenced enough; Khachaturian's Spartacus and Phrygia, especially the brass version; Holst's planets, esp Uranus; Beethoven's 7th; Gorecki's 3rd.