Those venues are plentiful, and a nice change of pace for visitors from puritanical countries like the U.S., where bars don't have dark rooms and gay saunas are almost non-existent.
But you do Amsterdam a disservice if you go just for the Horseman's Club. It's a beautiful city, compact enough for strolling, with dozens of interesting sights. Some with substantial interest to the beefcake aficionado.
Here is my suggested Three-Day Beefcake Tour
1. Start, of course, with the Rijksmuseum (Museumstraat 1), one of the great museums of the world. Unfortunately, it's closed quite often. If it happens to be open during your visit, get there at 9:00 am, and plan to devote at least two hours to Pietro Magni's David, Triton Blowing a Conch Shell (DeVries), The Fall of Man (Van Haarlem), The Striding Warrior (Van Tetrode), Mercury (De Keyser), and the gay couple Orestes and Pylades Disputing at the Altar (Lastman).
2. Don't forget the Discus Thrower in the courtyard.
I'm not kidding. Here's a censored view of part of it.
5. You've probably had enough museums for one day, and need some chocolate. About a 15 minute walk along the Prisengracht is the Van Soesdt Chocolatier on Utrechtsestraat 143.
Then retrace your steps along the Prisengracht to Raamstraat, and the Thermos Sauna (Raamstraat 31).
Get to the Anne Frank House (Prinsengracht 267) as soon as it opens at 9:00 am. It's very peaceful, and a little eerie, in the early morning. No beefcake here, but it's an impressive restoration of the house where Anne Frank and her family hid from the Nazis for two years during World War II.
Then turn left, down Westermarkt for the nearby Homomonument, the monument to gay victims of persecution (Westermarkt 1016).
More after the break.
6. Walk about 5 minutes across the bridge and down Kalverstraat, to the Allard Pierson Museum (Oude Turfmarkt 127), the archaeological museum of the University of Amsterdam. It features ancient Egyptian, Coptic, Etruscan, Greek, and Roman works of art, including many muscular gods, heroes, and warriors.
8. Finish up with a 5 minute walk south along the Damrak to the Adonis (Warmoesstraat 92), a sex shop with dark room.
Start off with some shopping in the antique shops on 9 Straatges (The Nine Streets). They are generally open quite early.
Then south on the Herengracht to the Bijbels Museum (Herengracht 366-368). It has antique Bibles, models of temples, and other Bible artifacts.
9. Head south on the Herengracht about 10 minutes to the Museum Van Loon (Keizersgracht 672), the home of Willem Van Loon, founder of the Dutch East India Company, who collected objects d'art from all over the world. The rooms are lavishly decorated, and there's a special exhibit, "Suspended Histories," with paintings of the colonial enterprise, including a surprising number of semi-nude male natives.
12. There are also some interesting statues, including the National Slavery Monument and "Vrouw op Man" (Woman and Man).
13. You'll need to take another metro to visit the gay bars on Reguliersdwarsstraat, or if you have the right night, the Argos Bar (Warmoesstraat 95) for the Horseman's Club. Don't worry if you don't measure up; the rules have changed, and it's now open to men of exceptional endowment and their admirers.
A good way to end your visit.
See also: Finding a Boyfriend at the Horseman's Club