I think the vast majority of saunas in Germany is "textile free", but also mixed gender. A rare few may have men-only days or hours. I don't know about others here, but in my experience, it is very, very not sexual atmosphere. It is, however, relaxing and I find it nice that people are very relaxed about nudity.
Saunas are usually adult-only (15+). So you won't have kids running around, but you sometimes may have a gaggle of teenagers. But mostly it's adult-behaving adults in there.
Textile free means you wear a towel around you when walking around in the hallways etc., but when in the sauna you take off the towel completely and use it to sit or lay on the bench. The idea is that your sweat should never touch the wood as it shortens the lifespan of the wood. They also may have the aufguss in the larger sauna rooms where the staff (fully clothed) would perform a "towel dance" to whiff the fragrant-oil-scented air all over the room.
Finland, on the other hand, usually segregate their saunas by gender. They also tend to take off their towels and sit naked on the towel. However, fathers do take their sons to the sauna, so again it's not really a sensual experience but it's amazing I think because then those kids don't get the nudity hangups the majority of the world seems to have.
In Helsinki there's the public swimming pool/spa in the centre of the city called "Yrjönkatu". It's housed in a BEAUTIFUL building, some parts of it may be a bit old but it's all clean and well-maintained. They have men-only days and it is nude for everything including swimming in a full-length swimming pool. They do have female staff, but the place is quite big.