List of terms non-Spanish speakers may find helpful:

Camara de Vapor - Turkish (steam) hot room
Camara Seca - Finnish (dry) hot room
Sala de Descansa - relaxation and rest room
Ducha Española - cold shower
Sala de Video - video room
Cuarto Oscuro - dark room
Hidromasaje - jacuzzi
Masajes - massages
Masajista - masseur
Pileta – pool

Buenos Aires Full Spa
Open Mon – Thurs from noon-3am. Fri – Sun Open 24hrs. Entrance Fee: AR$35. Check online for discount coupons. No Credit Cards. This is the largest and most popular sauna in Buenos Aires that attracts its biggest crowds after work during the week and after 2am on the week ends. Very popular on Sunday evenings and has a good mix of people. Facilities include changing rooms, bar/cafe, dry heat room, steam room, jacuzzi, gym, labyrinth, xxx videos, pool table, sun beds and private cabins on two floors. Masseurs are also available.
Address: Viamonte 1770 (Between Av Callao and R. Pena)
Tel: 11 4371 7263

Nagasaki Club
Open Mon - Sun 13h00 to 00h00. The club features wet and dry saunas, a voyeur basement, chill out area, communal jacuzzi, sex bar, and dark room.
Address: Aguero 427/431 (between Corrientes and V Gomez), Abasto
Tel: 11 4866-6335

Energy Spa
Open Sun - Thurs from 12h00 – 00h00 Fri and Sat Open 12h00 – 03h00. This is a relatively new and well equipped gay sauna with a range of modern facilities that include changing rooms, large dry heat room, steam room, a plunge pool, Jacuzzi, bar/cafe, small dry heat room, private cabins, porno video room, and dark area. A number of different types of massages and masseurs are available. Very popular on Fridays.
Address: Bravard 1105 (cross street Av. Angel Gallardo)
Tel: 11 4854 5625

Open Mon – Fri 12h30 – 00h00 Sat & Sun 13h00 – 03h00. This is a relatively small, fairly basic sauna offering dry and wet steam rooms, dark room, xxx videos, café/ bar area, with masseurs also available. Tends to be more popular with older men. Promo and popular Wednesdays.
Address: Av Pueyrredon 1180 (Between Mansilla and Paraguay)
Tel: 11 4961 7792

Homo Sapiens
Open Mon – Sun 12h00 – 00h00. Thursdays are popular.
Address: Gascon 956 (Between Rocamora and Guardia Vieja)