For 50s, I would think that something like "Swinging Down the Lane" (the Frank Sinatra version) would be a good pick. It has a very beautiful melody to it. Or maybe "I Could Write a Book" (again, the Frank Sinatra version). It has a beautiful melody, too.<br />
For 80s, I've always LOVED the song "I Just Died in Your Arms" by Cutting Crew. I think that song would be great for a chorus. Just make sure that the covert subject matter (it's not obvious, but still...) is appropriate for whatever function your chorus will be singing in.<br />
But for another FANTASTIC song from the 80s, you should do the cover of Nik Kershaw's "Wouldn't It Be Good." The cover is by the Danny Hutton Hitters. Their rendition of the song is beautiful with amazing vocals and an overall better vibe than the original.<br />
Best of luck!
Power of Love, Walk like an Egyptian, Girls just wanna have fun, girls on film, relax, don't do it.