As I mentioned in passing in my blog post here, i see my my dungeon built in a “node-mode”. With that I mean that each level consist of a number of distinct places, more or less independent from each other, a dungeon quanta of sorts. Suitable for a short evenings play. A handful of critters, some traps and tricks. As each node is a bit of distance from each other they won’t automatically go on alert from the sound of combat (as they usually should in many published dungeons. They become a microcosm in the dungeon macrocosm. And it is from these nodes rulers that the dungeon grows into a full fledged mega dungeon of Dungeon’God.
Each conflict (encounter) in a node empowers Dungeon’God and when enough energy has accumulated a new node buds into existence.
And how much energy is that, a tentative guess is that it should be equal to twice the level cost of five party members of that dungeon level. After each invasion of a party add the estimated encounter XP (very detailed in 3.5/pathfinder) and subtract the value of treasures the adventurers made of with, but add half of the value of any spent magical stuff as well as half of the XP lost by any killed PCs as well as half the total value of henchmen (as they aren’t resurrected)*.
As this XP energy goes down with higher level PC the Leveltenant quickly lose interest in engaging high level parties and just want to speed them on further down into the dungeon. Hopefully making some value by doing that.
The nodes grows in a patter similar to a Pascal’s triangle. With the exception of the first level lairs creating one other lair (and the starting lair that starts the dungeon creating two lairs) two Leveltenants has to cooperate to start a new node. The cost must be shared in proportion to their actual level. And will be populated by the stronger Leveltenant.
Between the Leveltenants there will be a complicated network of intrigues and deals that the PC may use or abuse if the become aware of it.
When a level is “cleared” by a party it will be repopulated from neighbours and someone will be declared Leveltenant (about d3+level HD).
Each lair has a connection to the surface world, but with the exception of the first three lairs these don’t have to be in the same neighbourhood (distance related to fibonacci series expressed as the natural logarithm in km, this will fast take you to other continent and dimensions in order to satisfy this distance, and thats actually the general idea).
* I use other indert method to gauge the XP and level increase of the players