What does it take for a den to gel?

This is a topic that someone could write a book about. I have had dens that took off like rockets and never faltered and dens that never could get started no matter what I did to help. There is a chemistry that happens sometimes that is a combination of parent involvement, support from the Pack, and the enthusiasm of the boys, all of which is often a function of the health of the Pack as a whole. Training of the adult leaders plays a big part in all this, but more than anything I think it is a function of someone caring enough about the program to see that the boys are actually doing a Scouting program. So often what happens is that boys assemble, sometimes in uniform, sometimes not, and then play for an hour or two and then go home. I'm all for playing, but that is not really a den meeting as far as I am concerned. I like to see the den leaders organize a series of meetings at the start of the year in which advancement goals are mapped out and meetings planned to accomplish the advancement goals. Often, the most successful den leaders divide up these tasks and assign a topic to each of the parents. That parent then plans the program to accomplish that advancement activity. This brings the parents as well as the boys into the Scouting program, and this is what I think ultimately make the den "gel." What do you think?