Jonathan Bernstein discounts Palin and Romney:
[T]he 2012 cycle will be only the third truly open nomination without a serious heavyweight in modern GOP history. Now, it may well be that Republicans are simply inclined to follow hierarchies (although don't ask Lisa Murkowski about that!), and that they saw Bush in 2000 and McCain in 2008 as more "next in line" than the others. But that doesn't really tell us that Romney or Palin will (necessarily) be helped by that tendency; it implies only that whoever does benefit will seem, after the fact, to have been the logical next in line.