I have put entirely too much time into Diablo 3 already, so I already have 5 pretty well geared 60s, one of each class. It seems best to play one to 70 and finish Act 5, unlocking the Mystic, THEN going back and starting my Crusader.
Then the Crusader will have Jeweler/Blacksmith/Mystic, 4th storage tab, and I can easily steamroll him to 70, potential weaknesses be damned.
Although I do feel a cold coming on, I wonder if I will be too sick to go to work tomorrow?