A friend of mine pointed me to a great piece over a great whiteboarding exercise.
Monster that I am , I’m thinking of ways to make this more fun. What if you made it a sort of competition? Take two experienced UX designers / researchers and get them to take turns, independently, doing the whiteboard challenge for the same design question. After, you can rank them via either a judge panel or an audience vote, based on criteria like Insight, Process, Creativity, and Communication.
The audience sees two different approaches starting from the same point and to compare the insights developed, and possibly get some perspective on their own practice.
Location-wise, it can either be done online via teleconference, or on-site as part of a UX social.