My ideal critical hit chart would be one column that goes to at least 250, ideally 300, with a roll modified by the critical severity. For more advanced options I'd likely work in weapon expertise somehow, but only slightly. Then, there'd be one of those for each weapon size/type variation (i.e. 1-H Slashing, 2-H Slashing, 1H Krushing, 2H Krushing, Piercing, Pole Weapon (Quarterstaff, Three Section Staff, Nunchaku, etc), and so on. I'd like to see one for each individual weapon, but having written critical charts I know that would be an insane undertaking unless you had a small army of very like minded writers to do the color text.
And I'm right there with Peter about the randomness of rolling a 200+ attack and a 01 critical. In a way it kinda breaks ones suspension of disbelief.