A boon for our beligured Kael:
Kael - inspiration struck recently, and it would save you time if you want to implement it.
I was thinking on your promotions aimed at harming specific things like 40% vs giants, 40% vs elves or dwarves, and it occurs to me that i rarly use them, becuase the dwarves, elves etc (maybe not demonic) get outdated faster than units can get promoted to them. As there are not tier 3 or 4 elves and dwarves (as a standard unit) it makes little sense to use a promotion when a more rounded one...40% vs. all melee would still apply to dwarves, and other units as well. Perhaps make the specific anti-type promotions a bit stronger, so its not silly to take.
IN this though i was trying to figure out how to improve your dwarves and elves. I of course, want late game versions - I'd love to be able to field an army of nothing but elves, or dwarves if possible and if it fits the theme im aiming at for that game. And it occured to me, the "equipment" tech might be what im looking for. Instead of creating a "whole new unit" that comes further down a tech tree, perhaps you could just create a new promotion (and building that that provides that promotion to all x-type units) that adds 100-200% strength to the unit. This is basically then a dwarven upgrade.
If you have your Dwarven Soliders Str - 3, Mine ability, Double-uber in hills, but your facing macemen and axemen (whom are stronger) and the like, you stop using dwarves and favor other units. BUT, if you build your "Dwarven Hall" Which provides all dwarven units with the "Stalwart" promotion, suddenly your dwarves are Str 3, Mine ability, Double-uber in hills, AND +100% or 200% Str. YOu now effectively have a new unit at the 3rd teir. The dwarf effective str is 6 or 9. The promotions he's earned however (Combat I, or whatever), would reflect the base strength, not this new uber strength - i consider that something of a balancing effect so this doesnt get carried out of hand.
This could apply to any units you dont want to create a whole new graphic for, but could easily create a new quick building and promotion for. (Building-promotion for new units built and normal promotion for units that have x amount of exp)
-El Scotto
EDIT: The balancing nature would work out well, as your dwarves and elves are tier 2 cost to produce, but with the upgrades they could compete (as a functionally new unit) in a tier 3 and tier 4 world. The fact that their promotions reflect their origional values, counters the cheap cost of the units late game.