I agree completely. I've been also to their classes, and to others' as well, and working well with data is a great blend of both art and science. Tufte's books explore that very well.

The whole topic of data visualization is a fascinating one, and lately I've come to think of it as at least as important as the db side of things. The overview of techniques article was a good one as a intro into the many different approaches possible. That same Stanford lab has produced a number of pioneers in the field (Tableau is one result, but there are also good competitors) that have made it very easy to explore data without programming skills. The premise is that much can be revealed from data by selecting the appropriate visualization tool. The catch is that it is very hard work to do it well (like most things, no?), and it requires a ruthless kind of honesty to be clear when one is just making a pretty picture. But it is a very enjoyable way to work with data, bring an aesthetic sense to data work, and end up with something simple and elegant (other than a great data model or sql query, which few can appreciate). By the way, an easily accessible source of highly regarded visualizations is the New York Times -- their work is often singled out for being high quality. Also Hans Rosling's TED talks are famous in this regard.