Movies employing music in a great way.

The Big Chill started a revival of 60’s R&B music.

The Blues Brothers has some performances by legends like Ray Charles, Aretha, James Brown and Cab Calloway that are iconic and with them all being gone, precious. Yes, it was a silly comedy but the music was epic. Some of the sound track music without performances is great too, Sam and Dave come to mind.

Another crass but legendary comedy with good music is Animal House. The "Otis Day" performance of "Shout" is fantastic. Sam Cooke is featured heavily.

Edit to add: The Wizard of Oz. That music has become part of the cultural subconscious. 

Clint Eastwood is another director who uses music very well.

John Hughes was brilliant in this regard with his timing and selection of particularly 80s tracks that fully captured the essence of his iconic films.

Apocalypse Now. The music is as much a part of those scenes as the visual. Wagner's Ride of the Valkyrie, Stones' Satisfaction, Doors' The End.

I'm not big on keeping track of directors, etc but the music in "Hell or High Water" is simply fantastic. I consider it outlaw country. Has a real edge to it. Fits perfectly with the scenes in the movie. Chris Stapleton performs Outlaw State of Mind - almost a country dirge. Played it last night!