Often I've noticed that, at least in the United States, the majority of tree kangaroo exhibits are indoors, fake, and mostly on the small side. Tree Kangaroos are often overshadowed by their larger and more popular cousins, wallabies and true roos. I think if presented in a unique way they would make an interesting exhibit. Where are the good tree kangaroo exhibits around the world? I found what is probably one of the best ones in the United States, at Detroit Zoo.
http://www.zoochat.com/562/tree-kangaroo-exhibit-detroit-zoo-42122/
http://www.zoochat.com/562/tree-kangaroo-exhibit-detroit-zoo-42122/