Just wanted to add, as old as this is, and even though I'm new, I'm considering crossplaying as Tifa or Aeris with my wife (though going as "friends"), and I'm more straight than most "normal" men, I don't even like watching porn if it involves a man and his genitalia; it grosses me out.
For some reason, seeing myself in something sexy, depending on what it is, does slightly turn me on however, not because I look like a man, but because I'm actually built more like a girl.
I also have personal reasons for wanting to do it, because I'm a philosopher and study psychology, and want to compare how women treat a similar personalities that are coming from a woman, when I'm used to seeing their reaction from a man. It also interests me, because I'm not a player, because I don't lead girls on for sex, but I still do know how to make a target hot for me, and wanted to see how they'd react to the same stimulus given from another female, that almost always works (different ones for different personalities).
So everyone has their reasons for doing it, some more out there than others... ^_^