My wife and I stayed one night at the Otter Lodge and it was excellent. It is close to the other two lodges, but far enough away that we felt isolated. The fire pit and grill are shared between the cabins, and we made use of them when no one else was there, but that's not a guarantee.
The cabin (one room with a bathroom and balcony) itself was clean and free of bugs, which was surprising because the property is tucked away in the woods. The jacuzzi on the balcony was great as well. Thunder Ridge is less commercialized and I think it is run solely by Susan, who helped us check in and provided a cart to lug our suitcases across the lawn to the cabin. She was very welcoming and kind and the breakfast muffins were a nice touch. Normally they would be baked by Susan herself, but unfortunately her oven had broken and hadn't been repaired yet.
Overall, it was a nice, isolated getaway, and close to lots of great spots in Hocking Hills. Can't beat the price either!