When I listened to a two-CD Bobby Darin compilation about a month ago, I also noticed something about his version of "That Lucky Old Sun." Each verse ends with some variation on "That lucky old sun has nothin' to do / But roll around heaven all day," and in the second and third verses, Darin sings the "around" with melismas. For the second verse, it's Bb G F Eb, and for the third, Bb G Eb.
This articulation has two features. First, there's a musical sense of the "roll[ing] around" because of these extra syllables at various pitches. Second, those extra syllables provide a sense of freedom. Earlier lines in the song that mention work ("Up in the morning, out on the job / Work like the devil for my pay" and "Fuss with my woman, toil for my kids / Sweat till I'm wrinkled and gray") are sung with the same number of syllables they're pronounced with (save for "pay" and "gray," which each have an extra syllable). "That lucky old sun" doesn't have these concerns, so it can "roll around heaven all day" with "nothin' to do," and that freedom is represented by this flexibility with regard to standard syllabic counts.
Listening to the Isley Brothers' version of "Lucky Old Sun" a few years ago, it occurred to me that the lines "Up in the morning, out on the job" and "Fuss with my woman, toil for my kids" exhibit structural parallelism. "Up in the morning" and "out on the job" are parallel, as are "Fuss with my woman" and "toil for my kids." (Even the plea to God to "Show me that river, take me across" has some parallelism.) This parallelism also illustrates the schedule that the speaker/singer operates under. In the same way that these lines are broken into phrases with the same structure, his time is organized according to his labor.
