Dylpickle373: Would you be able to add testificates (villagers) spawn in the non-ruined cities?
You can do it yourself. Monster spawners are special chests that can hold mobs, and will create copies of that mob. Special Block ID 330 creates a monster spawner with a Testificate/ villager inside. Since monster spawners don't need to be exposed to air, you could create a building *.tml that hides one under the corner of a room, and that room will produce about six testificates while the player is nearby. I recommend creating a 'pub' or 'ale house' building.
urfvfh: fo some reason my generator only generates ruins :/
Change the 'weight=' lines in your minecraft/resources/walledcity/*.tml files, or delete the *.tml files for cities you never wish to see.
SurpentK: if you set your wold generation to superflat will the cities still spawn??
No; I tried this myself. I know the superflat worlds bypass normal chunk generation, and I can guess that GreatWall/WalledCity/CAruins hooks into the objects that do normal chunk generation. Maybe after the mod API arrives, there will be hooks for chunk generation in both regular and superflat worlds.