There are two main gay areas in Amsterdam, one in the south of the inner city, the other, which I researched more thoroughly, in the Red Light District. All venues - non-sexual ones too - proudly fly the rainbow flag so you cannot miss them even though some of their actual street signs are obscure. Overall, it's rather expensive to go out here compared to, say, Berlin. It's also rare to have to get out of your clothes and to be able to store them safely, so beware of pickpockets.
FUXX (Warmoesstraat 96): A dance club cum cruise bar on normal days and weekends but on the first Sunday of the month they organise a naked sex party from 3 to 7pm. The cruising is on three levels, including a smokers level. The bar is in the basement and you run a card tab settling at the end of the day. Beware of drinks prices, a Becks beer sets you back €4, on top of your €8 entry fee.
You check in your clothes with the wardrobe person and then you're off. It got pretty crowded (you have to be in between 3 and 4pm) but not too much and as far as I could see everybody had a good time. All shapes and ages attended and it made for a fun free-for-all. There are no private areas so group play rules apply. You can get condoms but the main activity was oral sex. It gets pretty heated and especially the smokers' lounge was challenging for my lungs. A nice touch was the double bunk bed with comfortable mattresses which is an effective prop in group play. Every sex venue should have one.
Recommended, if pricey!
THE WEB (St Jacobsstraat): A traditional looking pub open from lunchtime with an upstairs back room, just off a main shopping street, Nieuwendijk. You can sit outside with your beer if the weather permits. Walk-in entry is free but you need to buy a drink before you are allowed upstairs. There is a locker room for your stuff (a safe option because warning signs of pickpockets are everywhere). Lockers require a non-refundable €2. The cruising area mainly consists of cubicles with glory holes. There is a separate rectangular seating area at crotch level so the cocksuckers don't have to steep too much and the suckees can sit and lean back. There is also a lockable sling room with bath tub and separate urinal. There were a lot of tourists judging by the languages spoken.
CUCKOO'S NEST (Nieuwezijds Kolk): Another traditional pub (but one tied to Heineken so it doesn't sell any other beer - best to get tanked up elsewhere beforehand) just around the corner from The Web. There is also outdoor seating in front. Entry is free and not buying a drink gets you told off by a grumpy barman. The backroom is in the basement and consists of two halves: one for smokers and one for non-smokers. They really went to town to accommodate the smokers and the afternoon I was there it was very busy. There are corridors with lockable cubicles but very little in the way of being able to lie down. A lot of Amsterdam gay sex seems to be happening standing up only. Some cubicles are connected with glory holes. It's customary to stand in the door and try to entice the meat you fancy into your nest. There is a separate smokers area without cubicles and which was actually air conditioned far more effectively than I have encountered before.
The wardrobe attendant was an Englishman dressed as a Met Police officer and great fun to joke with.
Recommended, if you can stand the smoke.
ADONIS CINEMA (Warmoesstraat 92): A sex shop with a multiple seater cinema in the back. It's open from early in the day and about 40 people can sit and watch the movies on a large screen. You pay at the entrance. A private viewing cabin is available but why would you want that?
Behind the screen is a tiny, well-lit backroom and toilet area. It includes a sling and a mattress at a good height so you can lie back and relax. Shame you cannot see the screen from the backroom. You can also play in the cinema area, the seating rows are spaced wide enough to allow easy traffic.
DIRTY DICKS (Warmoesstraat 86): Another afternoon option from 4:00pm although it is far less popular at that time. The bar and play area are integrated with bath tub and sling and cubicles. The barman told me it attracts a fetish crowd but the dress codes in Amsterdam bars in general have been slacking lately. Entry is free but you need to ring the buzzer to be let in.
Note: THERMOS SAUNA (Raamstraat 33): I didn't visit this because a €20 entry fee is way over the top, no matter how much they claim to be the best sauna in the Benelux. If you're under 25 it's €10 on weekdays daytime. Perhaps any twink among you could report back to me.