I think that anytime a thesis has to be developed, it has to come from the writer. It is so difficult to generate and defend a thesis statement in any paper. I believe that it has to come from the writer themselves and from this, stronger writing can emerge. With this in mind, topics can be given, but the selection of the thesis statement and the drafting of it has to come from you and you alone, in my opinion.
With this in hand, I think that a great topic for your inclusions might be to discuss what Salinger's work means in its assessment of life in the 1950s. What might the work be saying about this historical context? What aspects does it critique and how does Salinger himself reflect about this time period? I think that this is one approach to take. Another one would be to focus in on Holden, himself, and examine Holden in comparison to other characters in literature. It might be really interesting to assess how Holden would have functioned in other time periods and contexts. For example, Holden's disdain for "phonies" and the trappings of social acceptance would have been interesting to see play out in the 1990s. I think that this might be another area for you to pursue in the crafting of your thesis statement.