I have definitely had fun here in the past, but lately Sex On Sunday has degenerated into a smelly-old-people party. For a younger guy, it's like being surrounded by a bunch of shit-and-popper-scented crocodile-leather suitcases, some of which are desperate to fuck you. Amsterdam is a sad, un-sexy place.
Church is a very popular gay dance & cruise club at the Kerkstraat (near Leidsestraat).
Some nights have strict dress codes, others not. Some nights are about gay fetish and / or men only action while other days are just for dancing and drinking.
You enter the club via the coat check, where you can also pay the entrance fee (varies per night). You get a coat hanger, put your stuff on it and the hand it over to one of the coat check guys. For the underwear nights you can leave all your clothes there, and they give you a little plastic bag for your money, which you can put in your socks.
On the ground floor there is the bar (cash) and dance floor. On the upper balcony is a cruising space.
The toilets are in the basement, there you find also a shower (towels can be rented). Next to the toilets are some private cabins, and a large dark room.