The mudroom in the Tennessee farmhouse I grew up in was essential for shedding boots dirty from the barn and pastures, but here in suburbia, it would still be pretty nice to have one. Durable walls (board + batten, planks, or tongue-in-groove paneling painted semi-gloss) and floors, ample storage, and place to sit make for a perfect casual entry.
And a designated spot for the dog bed would be nice, too.