I think my fandoms are usually weird enough that I don't always see the point of AUs, if that makes sense. Like in sci-fi or comics fandoms you already have so many tropes just...sitting there, kind of for free. And some of them span long enough time spans that if you want high school or whatever, you don't have to do an AU, just, like, a "prequel" sort of thing.

I do like the AU photoset things that people make on Tumblr, though. Those are cool.