Hitlerland, by Andrew Nagorski is a useful survey of the attitudes expressed by Americans who witnessed the rise of the Nazis to power from the 1920s onward and their reactions to Nazi policies in the 1930s. The author integrates a number of important Americans, ie; US Ambassador Wiiliam Dodd, the journalist William L. Shirer, George Kennan, Dorothy Thompson etc in ascertaining what Americans thought concerning the events that they witnessed. If you want to get a flavor of what it was like for Americans in Germany as World War II approached and reactions to the rising anti-semitism under the Nazi regime this book should be of interest.