Glad someone mentioned "Caledonia", my wife and I used to sing together until she asked me to accompany her singing it - now we only do tunes. And I once didn't walk out when it was being sung, but only because I was waiting to sing the singer's least favourite song!

Apart from that, "Mack the Knife", apart from the Armstrong and Fitzgerald versions - I really love "Mackie Messer".

Anything sung to Crimond - the 1947 Royal Wedding's got a lot to answer for - Psalm 23 is great to Wiltshire or Martyrdom as recommended in the 1929 Scottish Psalter.