There are 2 spas here in the DFW metro area and I have gone to both of them. I started going there when my family would go to visit out of state relatives, because you could spend the night there, and I hate being alone in a big house. They are very relaxing places to hang out. I always start in the nude area, taking a shower and then soaking in a warm tub. Then I move up to a hot tub, then to the dry sauna. Usually everyone just sits there and sweats, but sometimes there is conversation. There are sometimes guys in there that have a towel over their laps, and they are generally the ones who are stroking themselves, let's just be real. Only very rarely does anyone say anything to these guys, and one spa is much worse than the other about this “activity”. After the sauna, one spa has a “drench” cold shower that feels awesome. I will drench and go to the cold pool to close my pores, drink a bunch of water and then relax for a bit before cycling again. The other spa only has the cold pool, so I will submerse myself there.
After a couple of cycles of hot-dry-cold, I shower and put on their “uniform” and go to the main area. There you can eat, or just relax on a couch or recliner. There are also other clothed co-ed saunas you can try with different characteristics. I have my favorites at each place. Since Covid, both now close at midnight, but before, I would always stay 24 hours. There are a number of places you can sleep, mostly on a heated floor with a mat. I think you have to be clothed in all of the sleeping areas, one of the spas has signs because there are areas off the locker room for sleeping, and it says clothes are required. Shoes are prohibited everywhere, so the floors are kept very clean, and it's nice to be able to go barefoot everywhere.
Both places also have co-ed pool areas where you wear swimsuits and I usually will go relax in the pool for a while, but this is usually the place I spend the least amount of time. I go during the weekdays almost always, so there is not usually a lot of activity, but I've heard the weekends can get out of control.