Humans do two things very well; we play games and we tell stories. Indeed, DR/BCP exercises combine both as we roleplay our way through a scenario.
Similarly, tabletop Roleplaying games (RPGs). such as Dungeons & Dragons, are all about presenting a scenario to a group of players and seeing how they react. Millions of people play these games every year and this has produced extensive critical analysis and large amounts of material on how to keep players engaged.
There are many useful tips and tricks from these games that can be applied to DR/BCP tests, albeit they tend to have fewer dragons and to involve more conventional monsters like power loss, DDoS or floods. Hopefully some of these will not only keep those involved more interested, but can also highlight and exploit some more novel ways of reacting to events.