Best for: Giving outdoor cats a midsize cat house with two levels—both a hideaway and a porch that can be their lookout post—plus a scratcher. Features: "Asphalt roofing is an effective protectant against rain, and the house itself should be made of weatherproof, sturdy wood," Dr. Conrad says, and both are features of this kitty abode. A front door flap helps protect against wind and other weather elements.