I personally like Cluin's use of the F#m after the D for the first two "go rounds," i.e., the "A" part, and the D7 in its place on the "B" part. To me, this seems to delay resolving the change from the D to the G, which you should get in the "B" part, when the tune as a whole is resolved, to say nothing of adding a bit of harmonic drama up front. Ungar wrote the melody, and that is incontrovertible, but there are some choices for guitar backing .... IMHO.