The Cincinnati Zoo would be a great place to host a children's birthday party. The zoo has a nice, relatively large picnic area that would be perfect for hosting such and event. Plus, there are so many things for kids to do at the zoo, that it would be a fun time for everyone attending. There is also a clubhouse that can be rented for a private party and you can even have your party catered. Contact the coordinators at the zoo for more information, but the zoo features lots of special activities for birthday parties, plus offers discounted admissions for attendees.