Skytterish said:
The ability to make rational decisions that have as little negative effect on others as possible.
I can see one little problem with that: A big reason why there's violence and terrorism and whatnot in this world is because, as bone-headed as these people might seem to us, to them, they're the ones being rational. Or if not rational, they at least believe it falls under the category of "greater good" or maybe even "It's beyond me" in the case of people following orders.
Bottom line: Rationality is just as subjective as anything else we humans try to use to justify our actions.
OT: I think everyone in the world should get super-regeneration/super-healing. Not like Wolverine regen powers, where a single living organic cell will eventually recreate the whole Wolverine (in some of the continuities, at least) but, I don't know, get a bullet wound, your body eventually pushes the bullet out and you heal up good as new. Running for an hour straight will be no problem, as the usual problems with soreness and lung issues and all that will be a thing of the past. In fact, with super-healing, I imagine people will become stronger, since their whole body can work at peak efficiency all the time.
No more disease. That's a deal-maker if I've ever heard one.