It's fun for me to take classes outside of the usual business-related courses to expose myself to new concepts and ideas. Some of my favorite learning experiences were from the acting classes I took a few years ago. They opened my mind and gave me a better appreciation for the craft.
I believe having a well-rounded education and contact with new ideas gives me more to work with when I paint or draw. There are so many more classes I'd like to take, language, music, dance, stained glass, bookbinding, glass-blowing, ceramics, speed-reading, history... I'd even like to revisit classes from high-school like advanced algebra and chemistry.
As I frequently say, too many interests and not enough time or money!