The addition I would really like to see

While, yes, there are a bunch of animals I would love to see included in the game (tufted deer, please!), the biggest thing I want is more stuff for the guests to do. I'd even buy a DLC that focused on it.

I wish there were more food options, both based on theme, like noodles and tea for my Asian areas or empanadas and agua fresca for my South American areas. It annoys me that, beyond a Mexican place, the only food I can place is very American feeling. Plus I would like to see some more things like cotton candy, funnel cakes, and frozen lemonade. All things I always remember getting in zoos as a kid.

I'd also like to see more things like the kid's soundboard and paw... thingie. Information boards about skeletal structures of animals with color coding comparing the bones to humans. I remember an exhibit from when I was a kid that had a display showing the difference between skin thicknesses and so forth. It had different fake skin cutaways so you could see just how think elephant skin was. Something like that would be great to make a kid's zoo area. Maybe even some domestic animals that have animations so you can make a petting zoo. Oh, and playground equipment.

Another thing that I would really want to see is a carousel. When I look at zoo webpages for inspiration it seems like every zoo has one. Even our crappy local zoo has one. I'd also like to see more hats added to the hat shop, and more shops selling things like books, t-shirts, and stuffed animals. Also, those little penny squishing machines where you would put some quarters and a penny in and it would press your penny so it was all stretched out and had a design in it. I'm old, do they even have those anymore? Or those souvenir machines that had a window so you could watch as it would make a cheap plastic animal? Plus, those wooden things with the cartoon animals that had a hole you stuck your head through and took a picture. Just little things I could throw down so the guests have something more to do than just whine and give shade throwing complements ("medium amount of thought", my ass, I spent a couple hours making that habitat you ingrate). Not only would it help make the guests seem more lively, but it would also be great to fill little spots without having to put down the same stone head or something.

In conclusion, while animals are important for a zoo (duh), guests are also a part of the thing. I feel they haven't gotten enough love so far.

TL;DR: While more animals are cool, and I won't complain about them, I wish there was more variety for the guests so it would feel more like a zoo full of people doing stuff in a zoo.