Taking a 1yr old to the zoo?

Erika • 💙 5.12.15 💙 11.29.18
I'm 32 weeks pregnant and really want to do something different and fun with my 1 year old niece before the new baby gets here and she isn't my only focus anymore. She spends a LOT of time with me (several days per week) and I am just really starting to get a little worried that I won't be able to make as much time for her when my own little guy gets here. 
I want to take her to the Cincinnati zoo because I love it, and she loves anything outside. I know she won't remember it but I think she will have a good time and be amazed at all the animals. (Her favorite thing to say is WOW! lol I think she'll be fascinated by so many new things.) 
My question is, does anyone have any tips or advice to make an outing like this with a (generally pleasant, but VERY active) toddler go smoothly? It's about an hour and a half from where I live and I don't want to get there only to have to come right back home. Also, where I'm so big & pregnant, I won't have as much energy as I normally would lol 
Advice please! :)