This Design Studio Method presentation by Todd Zaki Warfel is well worth the 28 minute investment if you are looking for a way to facilitate participatory UX design sessions.

I really like the parameters he puts around the critique portions of design iterations. Participants are instructed to find a few ways the design meets the goals, and a few ways the design could use improvement. This keeps people focused on the goals and moves the conversation away from why people like or don’t like a particular design.

via UX Matters