My local zoo (bioparc valencia) has the Madagascar walkthrough rather near the entrance, which has greater flamingoes and pelicans in a small lagoon area, with the fosas next to them. Flamingoes are rather common as entrance exhibits, making them kinda boring at this point. The fossa, however, are much more interesting as entrance animals, but based on the time of the day you may not see them (not necessarily bad though, but might not appeal to most zoo visitors)
my local aquarium has a more interesting set of entrance exhibits. L’oceanografic Valencia has the entrance building with a small lagoon which is home to some small bonnethead sharks and rays, plus a juvenile sea turtle. The exhibit is rather nice, but I don’t think there’s any railing, meaning people might be able to lean over and touch the sharks, which could cause injuries. The second entrance exhibit is a large bird pond home to a large assortment of waterfowl, which I personally find really relaxing and beautiful.