I've looked through some older footage of Show when he had some brief stints as a face and I have to say I've liked him best in that role. Seriously, get Show when he's having a good time and is able to be a good guy and he's got the potential to be absolutely hilarious. Show is one of the WWE's most solid workers, s'far as I know, so I think he's over due for a title push. He also seems to be doing a lot of what 'Taker has been known to do, that being working with some of the newer talent to get them over. He's done his job with The Miz, continuing his rise, and now he's moved on to Jack Swagger. If Swagger can pull a big win against Big Show it'll definitely help his wrestling credibility and Show as a face is something we haven't seen in a while. It's a win-win situation.
Now, that being said, I don't think that they should swing him all the way to a Cena level super-face. Not right away, anyways. If he went from being the mean and angry giant to Mr. Lovable in one go, he'd just seem as if he had multiple personalities, even though given the actual personality I've seen in his candid interviews he could very well do the "gentle giant" thing eventually, but not right away.