Night elf doodads aren't really neccessary IMO.
You have the NE buildings (hunter's hall, fishing village buildings & shipyard)
High Elf doodads: same:
you have 2 different "farms" in human campaign buildings, you have 2 dalaran buildings, 1 dalaran violet citadel, and 1 dalaran TFT observatory. I think it should allow you to make enough different buildings with those.
There's also a skin somewhere that turns the NE Hunter's hall into a HE building. I also believe Elenai made some High elf buildings.
Dwarf:
http://www.rondo.eu.tp/ (german site, but you don't need to speak german to click a download link...). The download size is around 4mb but the skins are shared amongst many downloads and you can reduce the filesize of them yourself. The dwarfs themselves aren't really "required" for the map anyway.
IMO those buildings look more human than dwarf to me. But anyway, dwarfs live either underground (mines) or in small humanoid houses, so that shouldn't be a big deal.
Undead: true, there aren't many, but if you enlarge the ziggurats (and include the 2 hidden zigs & spire) amongst the crypt, graveyard, necropolis etc. you could make an undeath city too. Enlarge it and it already looks more wowish.
Troll buildings aren't a priority imo. If you think that sort of racial buildings is a priority already, you'll need doodads for tuskarr, draenei, and hundreds of other races in
wc3.
Tauren? how did you solve that?
Underground:
http://www.wc3campaigns.net/showthread.php?t=81725
Although I agree there's a lack of decent snow models, I'd suggest you merge the "Northrend" and "Icecrown glacier" tilesets as they'll share the models anyway.