Last summer my ATF and I traveled to Amsterdam for a weekend to enjoy the red light district together, smoke marijuana with our morning coffees and also to spend a night at the ultra lux club Fun for Two
http://www.fun4two.nl/en/ (which is outside of Amsterdam about 45 minutes by car).
This place seemed to be a beacon for swingers, three stories of converted farmhouse plus private meticulously cared-for garden grounds w/a pool and patio (please do check that site to get an idea of how well-maintained and well-designed of a haven they created).
The main floor is a traditional disco with a buffet and open bar, the second story had locker rooms set up next to each other with some secret passage ways between the gendered areas. It was campy and made for locker room scenes. The other half of the second floor included a bathhouse style maze with lots of nooks and crannies and glory holes and benches and mirrors... all brimming with adventuresome couples and singles. The top floor was designed to look like a cobblestone courtyard with lots of shops and houses around the perimeter, which each individually opened up to reveal a private play room and some kind of kinky furniture (one had a paddling bench, one had a swing, one had a St. Andrew's cross and that's all I saw...). And of course there were benches and street lights in the courtyard around which to cruise and congregate.
It was epic - now I've been to amazing parties in the states that had very little infrastructural atmosphere but it didn't matter because of the people. And I would never say that you need all this jazz to have a great time, because you simply don't!
At the end of the day, its the people who make the party. And I haven't even discussed the specifics of the party. But rest assured that yes, Fun for Two was a super experience.