I've always found searching seeds when I reach a snow biome I automaticaly think "ahh avoid that and move on." I find theres not much in it. There is Red Wood trees and snow but I have always thought it needed something. You could do a native type tribe they fish threw the ice and what they catch goes to a community chest or something. I've always taken' this into consideration I would like your guys' opinins.
Anyways, on with the thread, I think they shouldn't add mobs to the biome, but instead turn towards the structure path.