I myself am going to go with Galapagos Tortoises. These huge marvels roam across hills, grasslands, and prairies in the wild yet in zoos they're almost always given a fenced flat gravel yard with a few rocks. I'm not asking for elephant sized enclosures for some tortoises but different levels of elevation in their terrain and different kinds of substrate would be great for them. This is exactly why Houston went from having one of the worst to possibly the best Galapagos Tortoise exhibits. Varied hilly terrain that survived the Houston summer and now the winter, sand, dirt, grass, stone, mud, and even a pool, and enough space for ten of these giants. They're living like royalty in Houston.