I can even see CLex in the context of Smallville, but by the time they've grown up and been slugging it out for several seasons of the assorted animateds, I'm having trouble seeing there still being attraction or friendship.

True, it's even hard to make it work in the later seasons of the show. *sigh* Gone are the days of blatant Clex from Season 1. I think that's why Smallville generates so many AUs.

Although now that someone has suggested Flash/Supergirl, I think they'd make an intensely cute couple. Not to mention an annoying one.

Someone else mentioned this just last night. I'd say they'd be super-annoying, but the cuteness potential is definitely there.