Giuliani has a reasonable chance to win the states of California, New York, and New Jersey.
Romney has some chance to win New York and New Jersey, and an outside chance to win the state of California.
McCain has a slight chance to win the state of California, but no real shot at New York or New Jersey.
Duncan Hunter has no shot at even winning California, much less New York and New Jersey.
A candidate who can't come close to delivering his own state adds nothing to Republican chances, regardless of his conservative credentials.
Don't forget Romney and Michigan.
His father was a very popular Govorner of Michigan, and IIRC Mitt grew up in Michigan and has strong ties to that state.