Coming from a place that is still a little close-minded, one of the things I liked more about Barcelona was its openness, especially when it comes to its gay scene. There is a whole neighbourhood we call Gayxample which is full of bars and clubs, and every time I go there, it ends up being a fun night.
One of my favorite clubs is Arena Madre. It is part of the Arena group, where they have different spaces and they organize different events. This one is open every day, and depending on the day, you can find events like themed parties or drag shows. The music is mostly pop/commercial and even though it is not usually my theme, I really enjoy it there. Usually, the entrance is 15€ but there is a small trick to get if for free. If you go to Bar PUNTO (you can find the address on the web page), I suggest you order a drink and ask the bartender for Arena tickets. You can get them for free, and it gives you free access before 01:30.
You can also switch from one space to the other, as they are pretty close.