This is what one teacher told us when we asked them the same question:
I start each class with 15 minutes of discussion, the topic is decided upon by the "boss" for the day.  He or she (rotated through the roster) chooses the topic and whether discussion is to be in pairs, small groups or whole class.  When it is pairs, we usually use reported speech to tell the rest of the class what we discussed.  Pron and grammar work can be pulled from mistakes made. Once a mistake is highlighted (without naming names) the class is charged with correcting it when they hear it again.  When the group is very disparate, I manipulate the seating so that complimentary learners are next to each other.  Even quiet and talking-challenged students rise to the occasion when they're "the boss".

Could be worth a try!