Good Jazz or Lyrical Duo Songs?

Me and my little sister are going to do a duo next year. We need to know what song we should pick. We either want to do a lyrical or jazz duo. We looked on the internet and couldn't find any good jazz songs. If we did lyrical, I would want to pick Footprints in the Sand by Leona Lewis but my sister doesn't like it. I am turning 16 and my sister is 10. Possibly for jazz or lyrical, a song about sisters? We don't want it to be too upbeat and no hip-hop songs please. We don't need to know soon we still have 2 months to think about it. Maybe a song like, All That Jazz, but not as upbeat. Thanks!!!!:)