Writing is key, and is both science and art. Creative writing allows us to hone our talents for communication and technical writing gives us the skills we need to express them clearly.
Music is also key in not only understanding our musical culture, but (and this is coming from a guy who can't sing to save his life) spending time in a musical environment has actually been proven to increase IQ.
Now the other arts I wouldn't call essential, but I would say it is a very good idea to spend some time in them.
Drawing, painting, etc. is the traditional "art" and is, as you say, wonderful for expanding the mind.
CAD is a nice mix of science and art as well and has various real world applications. A few CAD courses in my grade schooling have helped me out tremendously in the office.
Programming is more of a science than an art, but I'd like to see more kids taking programming courses. The things you can do with it when you really know the syntax in and out is fantastic, but even just learning programming theory teaches troubleshooting skills, technical thinking and many other skills.
And fingerpaint. We must have fingerpaint.




