Discovered this gem a few weeks back; the naturist Sauna Decor in
Amsterdam - all fitted out with art decor items from an old hotel from
Paris. The address is Herengracht 115 - a great place to relax and a
fairly equal mix of sexes.

http://www.saunadeco.nl/engels/index2.html
http://www.netnude.com/main/info/europe/artde041.html

It has a steam room (HOT), and two saunas and loads of wel laid out
relaxation areas. Also includes professional massage. Prices are very
reasonable. Its worth going to AMS just to spend the weekend there.