The happy wanderer (Mein Vater war ein Wandersmann) goes well with older people. German Edelweiss isn't well known I'd say.

Himmel und Erde might work (correct lyrics here)

A far better known round (to which still today new verses are added) is
He, ho spann' den Wagen an which seems to be sung to the tune of Hey ho, nobody home, so everybody could sing in whatever language she prefers.

Wolfgang