Come now, what else were you going to read about?

Brian Leiter plays the pick five books game on Nietzsche; his choices and discussion are worth a look. I haven't read Nietzsche's System, which sounds unpromising, but perhaps I will now do so.

Here's a good observation:

You mentioned that Nietzsche is fascinated by psychology. Do you think if he were around today he would be hanging around the psychology department, rather than the philosophy department?

Maybe not the psychology department in its current form! But he would be interested in psychological research. There are a number of themes in contemporary empirical psychology that are essentially Nietzschean themes. There is a large literature suggesting that our experience of free will is largely illusory, that we often think we’re doing things freely when in fact we’re not, that our actions have sources that lie in the pre-conscious and unconscious aspects of ourselves and then we wrongly think we’re acting freely. These are themes familiar to anyone who’s read Nietzsche and it’s striking that recent empirical work is largely coming down on Nietzsche’s side on these questions.

William James, I think, was having similar thoughts in the 1880s, but I'm not aware of any influence between him and Nietzsche.