My company would focus on North American fishes, reptiles, and amphibians. It would also dabble with other groups too, like songbirds, and invertebrates. Rarely, but on occasion, mammals. Or other species from elsewhere too, but they wouldn't be the focus. A lineup might look something like this...
Alaskan Blackfish
Oyster Toadfish
Colorado Pikeminnow
Artic Grayling
Gilt Darter
Eastern Newt life cycle set (eggs, larvae, eft, adult)
Marbled Salamander
Chuckwalla
Blanding's Turtle
Eastern Hognose Snake
Red Warbler
Cedar Waxwing
Atlantic Bay Scallop
Velvet Ant
And then to make sure other continents were represented, maybe...
Slow Worm (UK)
Eel-tailed Catfish (Australia)
Superb Fairywren (Australia)
Golden Mole (Africa)
Peacock Bass (South America)
Bamboo Shrimp (Asia)
Thai Bamboo Rat Snake (Asia)
You get the idea.