I like to get all the savannah animals in one exhibit (lions inc) and put in camels, roos and gemboks, plus the arabian oryx, dama and mhorr gazzelles (need 2 download) and sometimes i put in crocs, hippos and flamingoes. Giraffes and okapis work well. polar bears and grizzlys. All the tropical animals with moose. just stuff from the same sort of biome. u can mix different types of similar biomes, eg boreal, temperate and tropical forests. or try putting animals in different biomes that are found in the same sort of geological place. like nile crocs in a desert exhibit, or beavers in boreal forests, stuff like that