This is the best opener I have come up with yet. While I believe it is original, I am sure that other's have come up with variations of it, so I don't want to take too much credit.
This is perfect for opening a large set of women.
Walk up to them, and wait for them to notice you standing there looking quizzical (This is a Gambler technique to lower the energy of a group, so that you don't have to work quite so hard, and you can look great by raising the energy easily, later).
When they notice you:
"Hey, I've only got a minute but I was hoping you guys could help me with something. A little while ago I was dancing with some of my friends and I happened to notice a couple of cute girls out of the corner of my eye. As soon as they saw me look their way, they immediately started faux lesbian kissing and then smiled in my direction. Is that normal?"
BLAH BLAH BLAH (They respond)
"I guess it's hot and all, but I think it looks like they are trying too hard. What do you think?"
At this point, you can do one of two things. Either pick the girl who is really opinionated, or the one who is really quiet. In either case, look right at them and teasingly say, "Wait, your one of them aren't you?" As soon as you say that the rest of the women are going to look her direction. Pick the first one who looks at her, and say, "Oh I see, there's your partner in crime!" If your really ballsy, you can demand that they show your their technique.
I think this is a great opener because it accomplishes several things. First it easily establishes, that you came with friends and that you were having a good time (DHVing big time). Then it establishes that there were women who were interested in you (dhv). After that you infer that you are selective (with your questioning if the other girls were trying too hard). Then you show that you are funny while engaging a large portion of the group, and bringing up the energy that you carefully crashed when you made your approach.
At this point you have established a playful vibe, dominated the social group by assuming some familiarity through your cold reads, and you have the whole group engaged. You also have established a couple of inside jokes off of the faux lesbian thing, which you can refer to in the future. You will need to quickly transition to a new conversation topic as soon as you finish this opener. Since your whole premise is that you are at a club having fun with friends, and you have subtly broken into this set of women, I suggest starting a conversation about the club, or asking which one of them is "in charge".