This is my favorite Rogue costume:
I am a sucker for scarves.
And cloak/cape/hoodie combos. If I ever designed superhero costumes I would get the crap beaten out of me by Edna Mode.
I love the X:Men Evolution version of Rogue. That was my introduction to the character and Ryoko-demon cosplays her to perfection:
Link to her deviantart: http://ryoko-demon.deviantart.com/
Check out her 'Beauty and the Beast' cosplays; she brings Belle to life.