Orvis hot springs
My roommate and I spent a week at Orvis last year. We were in one of their tent sites. We found the establishment to be very clean, very relaxed and a fantastic experience. The Hot Springs has been there since the early 1900s and so the townspeople come and go without any thought...some clothed and some nude. Meals are still 'in town' and you need to eat early as most of the town closes up by 8pm.
I finally got to go last night. It was great! They are pretty busy and the camping sites were booked up. I ended up camping down the road at a different campsite. But I went for a soak in the evening. The staff was super nice. They explained everything. I saw them out checking temperatures on the pools. There were some people that were nude and some that weren't. But everyone just did their own thing. I found the pool with the temperature I liked the best. Btw, they are different depths, like 2 ft or 3 ft or 4 ft. They also have a cold plunge and a sauna. It's definitely worth stopping by!