Goodnight, A Thousand Goodnights - was the trademark parting song for Martin, Bogan & Armstrong.

I Also suggest

There's a Long Long Trail a Winding. (But do the whole thing, the verses, which are in a minor key, and the chorus that anyone who was a scout will know.)

That Old Gang of Mine. (you cant go wrong with a schmaltzy golden oldie.

Your nobody till sombody loves you. (ditto).