Greg Mankiw wrote a slightly surprising article recently, in which he advises students to take at least a class in economics, statistics, finance, and psychology. If you follow Mankiw's blog, you'll know that he tends to take fairly safe positions rather than bolder positions that might turn out to be wrong later. Maybe if you came out in favor of protectionism, he'd lash out at you. But on issues where the economics profession is more evenly divided he can be fairly meek. (By the way, I'm sometimes like that myself.)
What made the article a little surprising is that he seems to imply that those four areas of knowledge are more likely to be worth one's time and effort than the alternatives. It's possible that he's right, but this is not exactly an iron-clad proposition he's putting forward (and he basically admits as much towards the end of the article.) There's something very unMankiw about it.
Anyway, here's my take. When it comes to choosing classes, there are at least two things to keep in mind. There are practical classes, which might be helpful in one's career later. E.g. Of Mankiw's choices, statistics, finance, and perhaps economics fall into this category. I might also add accounting, computer science, and others as well. Yes, psychology could conceivably be of us in one's job, but I don't know that such a class is really much more important than many other alternatives, such as, say, learning a language or taking calculus or creative writing. So, I found that suggestion to be slightly odd.
Then, there are classes which might enrich one as a person, improving the way one thinks about the world, etc. Many courses could do this, but in my experience courses such as philosophy, history, and theology or some hybrid such as literature/philosophy can be great at this. I don't advocate all such classes. But a really good humanities class can really blow your mind. Maybe a history of Western Civilization or a study of philosophical classics such as Plato, Aristotle, Augustine, Descartes, etc. They can be rather thought provoking. You start to think about the grand questions. I think biology and economics can be interesting in that they can be used to study human affairs with analytical rigor. Also, anthropology and psychology (especially with a more biological focus) can be helpful as well. Often people see some common human behavior and just marvel at it, confounded. But sometimes it makes a lot of sense from an economic or evolutionary perspective.
E.g. I remember someone remarking in a philosophy class that she didn't understand why she felt like she always had to buy nice new things, even though from a rational perspective she knew she didn't really "need" such things for happiness. My answer was that such overly powerful acquisitiveness and gluttony can be thought of as vestigial traits. So, when you feel a strong craving to eat sweets all the time, it makes sense if you realize that your distant ancestors in the plains of Africa didn't see such things so often and it made sense for them to have a great love of sugar so that they would eat it when they found it. Such analysis can be easily taken too far and can be too reductionist (I think C.S. Lewis called it "nothing buttery.") But I think in moderate doses it is extremely helpful.
I haven't worked out in my own mind how much one should emphasize practical classes in college and how much one should emphasize the grand-questions-classes. But definitely take several of each.