One interesting way to use this would be creating a network that shows who James Monroe talked to and the connections between them as well. As president he talked to many people of influence and it would be fascinating to see who he communicated with. It could also be intriguing to see how those communications changed before, during, and after his presidency.
Another method would be to see the frequency of topics he wrote about to figure out what was important to him. This could be done using letters and documents that he wrote. Again, this could be compared to see how these views changed before, during, and after his presidency.