The content to be derived from other literary works depends greatly on what you choose as your thesis.
You could do a comparison/contrast of the leadership roles in Danish history vs. Scottish history, as portrayed in Shakespeare's Hamlet and Updike's novel VS. Shakespeare's Macbeth.
You could examine the change in the time period of the author's the subsequent focus of their works. The cornerstone of Updike's novel is Shakespeare's Hamlet, which focuses on the internal struggle of the protagonist. Updike, however, focuses more on the external conflicts associated with the shifting of power. How does this reflect the world events during the author's lives?
Consider a compare/contrast between Gertrude and Cladius by Updike and Rosencrantz and Guildenstern by Stoppard. How do both authors address the story through the eyes of secondary characters? How does it change the story and the theme of the original work?
Hope that helps!