Yeah, more primates would be fun. Zoos typically have a lot of them, and they could be incorporated into multi species displays. Smaller monkeys (like the golden lion tamarin) are sometimes in walk through aviaries too. We do have all the basic "great ape" species iconic in zoos, but we are missing any gibbon, have only one type of macaque, no baboon species (since mandrils are now thought to be more closely related to mangabeys), and there is only one new world monkey species (I'd like to see a howler monkey species). Monkeys are mostly diurnal and fun to watch and generally popular with zoogoers (they are generally awake and very active when zoos are open, unlike many carnivores).
They are messy little things, though, in the game and in real life zoos (from what I've read).
I still want wombats and a cuscus species too! Both epitomize adorable, imo, as well as being cool marsupials (comeon,
the wombat has square poops. Don't we want to see how the game will render this). Oh, and an armadillo species, and a coati (yes, they are carnivora, but they are different looking enough from cats and dogs in looks and social behavior to be pretty interesting).
Don't want much, I know.