Well, twoftmama, that's not exactly true. The gorilla especially loves the tire swing, and the gibbons will use the climbing bars and the swing. Gorillas also especially love playing with the bone (odd, isn't it?), as do many of the other ape family members. Most apes also love the figs and the orange feeder ball.
Although technically all the cats should use the climbing rock, so far almost none of them (including the lions) actually DO use it. It seems to have been a big waste of time 'winning' it, as many will tell you. It costs a lot and it's huge, but no one seems to like it. Bengal tigers especially DO like the rock pool, though! They spend a lot of time in it. In general cats like the bone, the small ball, the stuffed prey dummy and the car tire (not the one on the swing).
Hope that helps you keep your animals happy!:original: