Well, consider this, y'all:
We have European fallow deer. We have Bactrian and dromedary camels. We have llamas. We have red-necked wallabies. We have Indian peafowl. We have capybaras. All these animals are totally perfect for a petting zoo.
We have animal spitting behavior. We have guests handling butterflies. These are great for petting zoos, as well.
If we were to get a petting zoo DLC, I'm sure that it'll have a great update revolved around human-animal interactions. This would add a lot of life into the game, both with guests and animals. Guests won't be mindless pumpkin-eaters or soda chugging machines. They'll be able to properly interact with animals. We could have feeding stations, allowing animals to walk up and take food from guests. We could have animals randomly approach guests, and guests can pet them.
The animals could also be semi-exotic domestic species, like what we've gotten. Patagonian mara. Fowl, such as turkeys, junglefowl. Pheasants. Waterfowl.
If we get a WE, and it's along the lines of small parrots, imagine the excitement...