Imagine: You walk into a karaoke bar in Nashville and see Lionel Richie singing his cottony R&B hits with a bunch of country stars. Best vacation ever! OK, Rascal Flatts make “Dancing on the Ceiling” feel strained, and Jimmy Buffett doesn’t sound like he really wants to "fiesta forever." But these collaborations jell because Richie's style is so expansive, musically and emotionally; the steel guitar on "You Are" enlarges the song's unabashed gratitude. And when Little Big Town ease sparkling harmonies into "Deep River Woman," everybody in the bar, even Blake Shelton, knows better than to try to top it.

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• Photos: Random Notes

“Helen Wheels”

A rollicking good-time hard rocker, "Helen Wheels" was not about a woman but about Paul McCartney's Land Rover, the anthemic chorus voicing the vehicle's reckless joy as "she" took to the road. The song was added to the U.S. version of Band on the Run but was issued only as a single in McCartney's native U.K. "I like that because it's a British road song and there's not many of those around," said McCartney. "It's always Route 66. But Carlisle? How many songs have got Carlisle in them?"