It's hard to talk about philosophy. I liked my philosophy classes in college (one overview, mostly with a Hume/Kant/Wittgenstein/modern analytic bent, and a philosophy of quantum mechanics class), and I like reading Peter Singer, but the older stuff just gets very woolly-headed seeming. It feels like they always try to hide some equivocation under fancy text, starting with "we define X as Y", then jumping through a natural-language use of X to get Z, then assert "Z is Y".
For example, I may just be a heathen, but Nietzsche's whole style seemed to be boldly asserting things, making fun of anyone who thinks otherwise, yet rarely bothering to make an actual argument.
I like the idea that everyone should take a semester's worth philosophy course somewhere along the way, but I don't know if it would do most people any good. An actual rhetoric course, with a focus on logical argument, may do better.