1. The wastefull life of the rich, Gatsby has all the money in the world, but he still does not get Daisy. The rich destroy everything in their way. ex. the murder of Myrtle meant in a symbolic way also. The excess of money implies the death of the American Dream, so in simple words, they find no reason to work hard for their money.
2. The obsession of the lower classes with the rich, Nick follows Gatsby everywhere. Fitzgerald is trying the emphasisze the relationship between classes.
3. The 20's is characterized as an era of moral disintegration,which can be seen through the greed and cynicism in the novel.
4. Their is also a notable difference between the two types of rich classes. The West Egg residents possess the grace of aritocracy, and live in a desirable and welcoming home, whereas Gatsby in East Egg is newly rich and lives in a wasteful mansion
5. You should also take into account the weather, geography, (the vally of ashes: death, destruction, hopelessness), the eyes of Doctor T. J. Eckleburg are especially important, they represent God looking down on society and judging its moral decay.
I reviewed this book in my AP Literature class also.
E-mail me if u have questions, I love talking about this book.