There is a particular kind of evening, after a long bath on a cold night, or that first swim of the year when everyone comes out shivering, when a towel either does its job or it doesn't. A large towel is the difference between wrapping up and actually feeling warm, between drying off and just moving the water around. I think about this every winter when the heating bill arrives and the only comfort left in the house is a towel big enough to disappear into.
These work hardest in bathrooms that see real traffic, a family bathroom, a guest room near the pool, a rental where the radiator barely works and the towel has to make up the difference. They suit a house with kids who flop onto the bath mat and need wrapping up like a burrito, and they suit a quiet apartment just as well, because one good large towel can replace three mediocre ones and free up an entire shelf. In a small bathroom, a couple of large towels on hooks will fill the wall and make the room feel finished in a way that a cabinet full of folded ones never does. They sit well with a simple hook or a ladder rail rather than a crowded rack, because a towel this size needs room to actually dry between uses, not to be stacked three deep where it stays damp and starts to smell by Thursday.
If you own none of these yet, start with two, not six. Two large towels in a size that actually covers an adult shoulder to knee will teach you more about what you want than a matching set bought in bulk and never fully used. Get the size right before you worry about anything else, because a towel that is technically large but thin and skimpy will never feel like enough, no matter what the label says.
For color, go with white, a warm gray, or a deep clay rather than anything pale and trendy, because white bleaches clean for years and the darker shades hide the inevitable fading from detergent and sun. Avoid anything with a printed pattern if you want it to still look decent after fifty washes. Plain and substantial beats decorative every single time in a towel this size.
Next to it, I would put a simple hook low enough for a child to reach, and a small stool nearby for the towel that falls on the floor exactly once before everyone learns better.