Palin has a good shot of gaining early momentum by winning Iowa and SC... but she has no shot at winning the presidency as she has much too much baggage. Somehow the Repubs need to derail her before she hijacks the process and derails them.
Romney would be a credible candidate, but the fact he is Mormon is a non-starter for the Christian funtamentalists that view Mormonism as a cult. Moreover, his MA health reform was the foundation of the US health reform, so he would be a weak advocate for those that do not like "ObamaCare".
Huckabee is a credible candidate, except I don't see how a creationist can win. He would appeal to the same elements as Sarah. If the Repubs can not derail Palin, Huckabee ends up lost on a siding early in the process.
Pawlentty looks like an excellent candidate. He is good-looking, well-spoken and intelligent (presidential material) and reasonable (which means he will lose tea party support and thus never get the Republican nod)
Christie is a romantic choice because of his upset and hit-the-ground running style in New Jersey. He has some possibility, but we don't know enough about him.
Not much of a bench on the Republican side at the moment.... but they need help, starting with hijacking Palin before she hijacks them.