Frivolous is a shit hole! And during the week more so. there is nothing classy about it and the one time I was misfortunate to attend it was full of creepy guys.
I recommend Avarus and Insomnia for a one night experience. During the week, the places are not as busy. As has been stated, it all depends what you are looking for or what you would like to experience, be it taking part or just observing.
If you here on a Sunday, Go to Avarus Wellness. It is usually a good crowd, I enjoy the Spa and Sauna… its always fun and Jenny is great when she is doing the sauna. After you do the sauna, there is a short pause and then they have chocolate in the wet sauna where everyone rubs chocolate over each other and things go wherever one is comfortable. It is a good way to introduce yourself or let you interest in someone be known. I don’t speak German, and have met lovely people, not all that I am intimate with there. Insomnia is Great on a Friday if it is Master and Servant or Angel in Bondage. The DJ and music is more to my liking on these nights… so don’t discount a Friday at Insomnia, I prefer it to the Saturday… its mostly a hedonistic club rather than swinger… but it depends on the event and night.
Obviously, I am not your age group, but I know what it is like to be new to Berlin recently and my comments are not with agenda, as I went to Avarus last week, and unless I am meeting friends, I generally don’t go.
Good luck and enjoy
Noel