You could always throw in some practical application demonstrations. Here's some of the ones I like:
- Hanmi handachi techniques with nage sitting in a desk chair (or for something more humorous, try a toilet!).
- Shomenuchi iriminage with uke wielding a broken beer bottle.
- Slipping on something slick and showing how good ukemi can help prevent broken bones.
- The gun in the back or knife in the face defenses are always thought provoking.
- "Encouraging" an intoxicated friend to get up and moving using sankyo. (actually did that for real a couple weeks back..worked great!)
However I agree that randori at the end serves the same purpose as the grand finale in a fireworks show.