Hi-I was told that this place could use some suggestions (particularly on the demihuman front) to try to keep the branches of these room trees even, so here I am. I'd just like to stress that what I'm suggesting in this and subsequent posts are merely suggestions, and that I have no right to assume they'll be used nor that I'll receive any compensation if they are. If people ignore me, berate me or tell me to get lost, that's just fine-but unless it's the guy who actually owns the forum saying so, I'll just keep going whenever a thought occurs.
So...
Hunter's Hut: works for either the Cutthroat Camp or those sneaky kobolds in the Warped Warrens, providing units that are fairly similar close-up but at least have a shortbow or crossbow to add a little damage when they're in the back.
Padfoot Patrol: goblins are known for cowardice, poison and swarm tactics. Only one of those can be put to good use in this game, from what I understand of it, so why not train the horrid little greenskins in the arts of the rogue? A padfoot is a good dodger and weaver, but the little club it wields is far from impressive; these guys are better at delaying and wearing down a group than they are at actually killing. On the bright side, they may pick up a little of one resource or another as they go... if it's deemed necessary to keep them useful.
Demonic Demolition: when the demons from the Portal got their metaphysical hands on the Grotto's denizens, was there any doubt they'd make walking bombs out of them? Don't expect them to survive many attacks, because these shambling near-corpses full of demonfire are in no shape to dodge and were literally made to split apart easily. But they will do plenty of damage if they manage to get up front and throw themselves at the enemy line. Even if they're destroyed before they attack, the splash should be good for something.
Speaking of demons, the Lemur's Lectern is a marvelous room for inspiring your fell forces to fight for their lives and demoralizing the good guys. These formless beings of dread can be pressed into more mobile service, lashing out psychically at the heroes and shrugging off devastating blows because of their high armor defense (or really just the fact you're swinging that sword through formless dread). Since Lemurs are technically wrathful spirits even if they do serve demons, this may be a better combination with crypt than stand-alone.
The 'Armless Armory is classic Seedy Cellar, full of rough blokes who do a very poor job of pretending that they aren't up to no good. The combination of good gear and bad training makes them a force to be reckoned with only against heroes with similarly poor training-they'll get taken apart by experienced adventurers. Of course, the same likely holds of any second tier unit without good backup.
According to the notes I took, that leaves one group that doesn't have a second tier room (well, two, with the second being the Cutthroat Camp or Warped Warrens, but I'd still call that pretty good for extemp work); the dark dwelling, which already provides dark elf warriors. Alright, how about a Stifling Stables, so named because the lizards housed within have toxic breath? They'll spew their poison from farther out and deliver a good solid bite when they're close-in. Depending on how you want your kobolds (some of them are essentially rat-like lizards, others are cunning and related to dragons), this could be a second tier for them instead-or a joint drow-kobold effort. If so, may I present an alternative for the dark elves?
The 'Sanctum' of Sacrifice: your denizens are taught that this is a place of healing, so badly wounded creatures will automatically enter if they pass through this room... where dark elf priests throw them onto blood altars, sacrifice them and pay you a portion of that creature's hiring costs as thanks for helping them keep their dark gods appeased. You can even hire them-the mere males in a power structure as matriarchal as the drows' are never taught the really nifty skills for smiting your opponents, but they do have healing and defense-buffing cantrips for when they're in the fourth and third positions, respectively. No wonder your denizens believe this 'Sanctum' is really about healing.
One final thought-what would be good for a Howling Hollow, which clearly needs to exist given the naming structure? A collaboration between the Lupine Lair and something else, of course, but... the demons for hellhounds? The goblins for grotesque wolfspiders? Maybe even the dark elves for (a generic version of) displacer beasts?