Guys and Dolls is regarded by some as a perfect musical. The uneven movie and some poorly received revivals have reminded us that it is not fool proof. You'll notice very little Nathan and Adelaide in the synopsis. They get far too much material to be dismissed as "supporting roles" but Sky and Sarah most definitely carry the plot.
But then there' s not much plot in act two either. Damon Runyon's original story, The Idyll of Miss Sarah Brown, ended with Sarah rolling the dice for Sky's soul. The dice rolling goes to Sky in the musical leaving Sarah little to do in Act Two but sing "Marry the Man Today." None of this is a negative. It's just interesting to re-examine the "perfect" musical's structure after some time away from it.