I tossed a few bullet points up there, but figured I'd elaborate here; since it's more conducive to discussion. 

Having everyone who is currently in the hall involved in any lesson before the regular dance does a lot to help inclusion. It lets everyone meet more folks than during the mill around between dances, and sets the expectation that new dancers will dance with experienced dancers and vice versa (assuming you're including partner mixing, which I strongly support in most circumstances). I try to keep my lesson to less than 15 minutes, so it's not a big obligation to the experienced dancers in the hall (and continue to welcome people to join if they get there late).

Do you go as far as to encourage regulars to show up early to be in the lesson?  Do you merely invite, strongly encourage, request people in the hall to participate in the lesson?