For Gangbang scenes, try Asa Akira is Insatiable #1 by Elegant Angel. The first scene (the Gangbang scene) takes place in a adult theater. Very moody, dark and sexy. Asa Akira wanders into a porn cinema and men begin to fondle her. It's a long scene that builds up in strength slowly, it's very intense indeed. As it teases you somewhat (you're never sure they're going to actually fuck her), this is a great scene to start with if you want to get into that genre. Yes, lot's of flirtation and everyone starts off dressed.
Another one is the final scene in Wasteland (again by Elegant Angel), with Lily Carter and Lily LaBeau. BUT, my suggestion with this movie is to watch the whole thing from the beginning. All of the scenes are hot and very personal, and the ending will blow your mind. I won't spoil it as the surprise is the key, but it's more than one guy to a girl, put it that way. There's also lots of girl-on-girl in this film so your wife needs to be cool with you watching that.
For DP scenes but not necessary gangbangs, check out some of the stuff by Daring! Media. This is pretty classy stuff that's artfully made. The movies to look out for in particular is the stuff directed by Kendo. Also, check out the movies made by Jack the Zipper. It's sensual stuff with a somewhat 'dirty' feel to it, most of it is either one-on-one or girl-on-girl, but he does some two guys to a girl sometimes too. Highly recommended for those who want to see a bit more than just people fucking on a couch.

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