You could look at Elvis from a sociological perspective, and not just a musical one. Remember: he was born in the south in the middle of the Great Depression. This shaped his personality for life. It also caused many people to look down their noses at him. Why was Elvis reluctant to play New York? Because it was a big city, and not just any big city, but *the* big city. Elvis had previously stuck to touring the south of America. His hometurf. But why the big fright over the big city? I think it speaks to the North/South divide in America that began with the Civil War and still endures to this day. It's a topic that doesn't get much coverage and I think it would be fertile ground to build an essay out of. Remember, also: Elvis sang "An American Trilogy" which celebrates/commemorates the involvement of every side (North, South, slaves) in the Civil War. But it begins with: "Oh, I wish I was/In the land of cotton". So Elvis was affirming his love for the south even as he sang it. Something else: Albert Goldman came from New York. And, if you know anything about Goldman's writing, you'll know it's extremely racist towards the south more than anything else. Why do many intellectuals continue to slam Elvis today? Why are people from the south often parodied and ridiculed in the mass media? Could it all be something to do with that North/South divide? There is an unspoken prejudice that lingers still.
Anyway: that's my idea from me to you. There are many paths to take when writing about Elvis.