"You Can't Always Get What You Want" (The Rolling Stones)

Sitting at the very end of the album Let It Bleed (1969) is the epic-length "You Can't Always Get What You Want."  It basically was Keith Richards and Mick Jagger's response to The Beatles' "Hey Jude"—purely from the standpoint that the Fabs had successfully crafted a 7-minute hit song with strings and a singalong chorus, and the Glimmer Twins felt compelled to shoot for a similar goal.
"You Can't..." opens with a tongue-in-cheek a cappella choral intro, performed by the 60-voice London Bach Choir (who ultimately requested that their name be removed from the performer credits when they discovered the album contained songs with themes ranging from serial killers to shacking up).  The track then shifts gears, making you think it's going to be an acoustic tune in the vein of Blonde on Blonde-era Bob Dylan—that is, until the drums, organ, and backing vocalists spring to life and reveal the song to be a gospel-inflected R&B number that digs down as low as it soars high.  
Throughout the song (and album, for that matter), the common thread is Jagger's weariness with the 60s—the drug scene, the political scene, the free-love scene, etc.  Even when Jagger is singing about a fairly lighthearted exchange with a friend over a cherry cola, the friend's response to Jagger is the word "dead."
While that might sound like a celebration of bleakness, the feeling is actually one of resolve: you don't always get what you thought you wanted; but, in the end, you get what you need.  Pretty sage wisdom.