There are other good combos, of course.
This observation by Allahpundit over the Christie/Walker dynamic in the primaries is worth noting:
One crucial thing that righties learned about [Scott] Walker during and after the Thunderdome in Madison over collective bargaining is that the guy simply will not bend on a policy he believes in, no matter how much acid the left spits at him and how far into the tank the media goes for Democrats in attacking him. He’s unflappable. That’s hugely significant when you’re thinking of throwing your vote to a guy who isn’t the most orthodox conservative in the field. The big worry about [Chris] Christie is that he’ll be wooed by media adulation of his charisma and his own rhetoric about the glories of compromise into governing even further from the center than people think. That’s less of a worry with Walker, the guy who became a right-wing rock star precisely because he wouldn’t compromise.