In the best of all possible worlds, we could all go to see all zoos and aquaria for what each has to offer individually. Why not do them all, plus Staten Island and even the new Sea Life aquarium in the Meadowlands?
@Hipporex reached out because he has limited time and wants to learn ways of seeing the most species on a trip limited by time and money. I acknowledged that individual species like sea otters or ducks might warrant a trip to the small zoos, but offered him the costs to visiting these. It's all relative. It's not "Are the small zoos worth seeing? but "Could he get more bang for his buck seeing something else?" or what you haven't considered, frankly, "What would be have to GIVE UP if he were to spend time on the small zoos?". That's the issue he sought our opinions for, not just dogged defense of our home-town teams. 6, 12, 18 acres is MINISCULE compared to all of the 100+ and 200+ açre zoos we've been discussing, and I stand by my assessment that the return on investment of time and money can't compare to what he could get by using those resources to visit larger zoos and aquaria with more rare species as proposed by others in either the NY/Philadelphia/DC corridor or the Chicago area.