A smaller, more manageable Mansion buried deep in a hilly Roofed Forest, this one's a slight trek to get to, but an enjoyable one nonetheless. You'll spawn next to a ravine that borders a Village (both convenient places to pick up early resources!), and then it's just about 1000 blocks through the forest to find this quaint Mansion. Also near the Mansion are some Extreme Hills, Plains, and even a spot of Spruce.
Village: -146 100 68