Like the Venn Diagram, the KWL chart is a strategy that I try not to overuse. I've had instructors who latch on to one or two strategies and use them in every unit and this practice bores me. I'd rather use a strategy such as this one sparingly because it can be very fun and cool and useful but not if it's overdone.
That said, I've been using the KWL with my sophomores for quite some time. I like to use it as a pre-reading activity before we read Macbeth and The Merchant of Venice. I like this strategy because I have the same students (for the most part) when they're freshmen and I know that we complete a huge Shakespeare unit and webquest. I do not want to repeat this experience for them, so I like to honor that they may already have some knowledge (K) about Shakespeare from the previous year. This knowledge often reminds them that they've forgotten some information about Shakespeare, so this leads them to identifying what they'd like to know (W) about him. Once they're online and they have freedom to search around as they like, they often discover information about the Bard that they'd never known before because I'd always given them the sites or led them to information. Once they are on their own, they often discover some not-so-savory information, which peaks their interest in reading more from this saucy, controversial author (L).
The way this activity is carried out and presented also creates a powerful visual in the room. Others who're reading Shakespeare with me in other classes are drawn to the visual and comment on it often. I like that the end product is easy to understand and demonstrates and growth and gathering of knowledge in a way that a poster or Popsicle stick replica of the Globe Theater might not.