Ok, small ramble ahead that probably doesn't make much sense.
I strongly disagree with the notion that you need to use UC pairings or extreme AUs to think outside the box. To pick one example, ArchAngel1973 and xmag are writing a terrific CC story (The Man Who Didn't Belong) that is far from your usual canon fare. Their AU epic The Lost Child is an AU that shows Michael in a different light, what he might have been like if he had been found and adopted into a loving family. He is however, still very much the Michael Guerin we know and love.
For myself, I will read AUs if the characterisations are true to the show. That doesn't mean that I have put myself into a little box of ignorance, but what it means is that I'm up for anything, as long they still resemble the TV characters that I fell in love with in the first place. Writers like ArchAngel, Katjen, Chicky, Misha, tequathisy and nibbles2 have shown that it's possible to keep the gang in character and write some awesomely creative stories that either deviate well away from canon, or at the very least have written superb non-run of of the mill canon stories without breaking up the TV relationships (which are the ships that make the most sense to me). Liz might be a stripper in Gold Diggers but she is still recognisable to me as canon Liz and I can see the true essence of M/L from the show, even though the setting is vastly different.
But Liz as a bad ass who attracts Michael, Kivar, Dean, Alec, Sark, Spike, [insert whatever 'bad boy' you wish here]? No, I don't believe it. Her character as I know it doesn't fit with Michael's so unless you change it completely, I won't find it believable. Same goes for Max with Maria. And if character personalities start changing or switching, then I might as well read a fic from a different fandom or a romance novel. The characters as presented on the show are what drew me and are what keep me here in Rosfandom now. It doesn't mean I'm totally anti-UC, I get and love the idea of Kyle/Isabel and I can even see where Mi/T shippers are coming from. But it has to make sense to me.
Everyone's different though and that's the beauty of fandom, there are many different stories and pairings to choose from, and they are for most part marked clearly to avoid butthurt from rival shippers. If they aren't marked properly, well that's another rant for another time.
