I really enjoy exhibits that have harp wire as a barrier (along with the hot grass for the bobcats in this photo) because the sounds and smells of an animal become distinct. Glass is always fantastic, but to hear a cat padding across its enclosure and emitting a noise can be a pretty cool experience. Memphis Zoo has some harp wire in its excellent feline section, and I even have a photo somewhere on ZooChat of a lion almost directly against the wire. There is a slight sense of danger at such a moment, as what separates visitors from a big cat is only a tiny set of wires.