Not a fan of panels or of lightning talks, either If you have people with very deep expertise present, give them the chance to explain it at length, preferably in a somewhat interactive format (not always practical at large events). I'll very happily listen to a 30-minute or hour-long session from someone who has devoted the last ten years of their life to some topic, provided it's even a smidge accessible Otherwise, focus on enabling small group and one-on-one discussions