I'd try to concentrate on the features of film that are more likely to differentiate it from digital, but I'd also try to highlight anything that shows how film is even more viable in a digital world.
I might try something like this:
1) Shoot something in Black and White that is capable of being made into a very good print, but also capable of being scanned effectively.
2) If possible, it should be on film that is at least MF and exhibit shallow depth of field - something that is fairly hard to do with the smaller sensors prevalent in digital.
3) Show the group a scanned image on a computer screen. It should be reasonably impressive in this mode.
4) Then show the group an original print, on at least 8x10 paper.
5) Then, show the group a number of different versions of the same print, reflecting different printing decisions, or paper surfaces, or toning choices.
6) Then show the group what the original negative looks like, highlighting how it can be stored compactly and safely for long periods of time. If the negative was shot on a medium format or larger camera, you might want to demonstrate the camera as well (35mm cameras are probably not exotic enough for this purpose).
If you really want to try a gimmick (and I'm not sure how easy or practical this would be to do) see if you can find out ahead of time how many of the group have cel phones that you can email a picture to, and what their email addresses are. Then, when they have the good photographic prints in front of them, email the resized digital versions to their cel phones and ask them to view and compare the cel phone image with the photographic prints.
I would be concentrating throughout on the flexibility and adaptability of film, even in the digital age,
Finally, if possible and the negative lends itself to it, it would be great to show them an even bigger print - at least 16x20, if not larger, to highlight the capability of film.
You might consider another similar approach - use a digital projector to project a file scanned from a colour slide, and then follow it up with the original slide projected using a good slide projector.
Just some thoughts, hope they help.
Matt