It'd be cool if certain houses were more favorable to certain units. For example, one could prefer divine units like the Arachne. Another could prefer War Spiders. Maybe another would prefer Infantry. The benefits would be that if you select a unit to be joined to certain house, it would have a small bonus like strength, bonus against certain units, etc. I don't know; that might be a lot of work for you guys. Cuz you would have to make something for the other civilizations. A system based off of the basic premise but with different focuses specific to the civilization. But just figured I'd throw it out there.