Interesting question! There will be lots of angles for discussion from this starting point - I'm looking forward to reading them.
I would really like to think that Shakespeare is relevant to the learning of all students, if only because he provides such great examples of use of the English language that we are all attempting to learn and use for communication. Analysis of common phrases in use today that he introduced can be a great setting for all kinds of activities. His use of descriptive phrasing is unparalleled - the examples are priceless even if the exact words aren't in use in today's world.
I must admit, I'm not sure of the value of teaching Shakespeare to students who are low ability or motivation, clearly headed for vocational training classes with minimal literary involvement in their life's activities. Maybe what I'm looking for with these students are some ways to present a few shining examples, not an in-depth analysis. Suggestions/other ideas, anyone?