I've been to Apollo Splash Club and Der Boiler and I would definitely say that the latter is the better of the two and it's by far the nicest sauna I've been to. Sunday afternoon/evening it's very busy although even midweek it's still got quite a few guys there. It's located in Kreuzberg on Mehringdamm right near Curry 36 and Mustafa's Gemüse Kebap (which I recommend). It's entrance is onto a small laneway that leads off from the street. I'm pretty sure Apollo Splash Club has regular foam parties although the steamroom where the foam is isn't the biggest room.

Lab-oratory is probably the most well known sex club in Berlin. I've not been yet but a few of my mates have and have said it's great. Do check their website though for what event is on each particular night as there are some very diverse theme nights. Triebwerk in Kreuzberg/Neukölln is relatively small although I've always found it pretty decent.

For nightclubs SchwuZ (also on Mehringdamm) isn't too bad - there are 3 rooms, which, when I was there, had different genres playing - pop/more mainstream, techno and electroclash so a decent variation. KitKat Club (which is a slightly more mixed crowd) has regular parties on Friday and Saturday nights although they have a strict fancy dress/fetish dress code. I've only been on a Monday night (tech house music and when there is a relaxed dress code) and although it was quiet found it enjoyable.