The only reason I'd vote for Romney is the same reason I voted for McCain, i.e., if he's the nominee who's up against 0bama in Nov. '12...
Unfortunately, this time around a vote for Romney will simply be a vote for Obama and, in particular, a vote for Obamacare. Do you really think that liberals/democrats would just sit passively by and ignore the fact that Romney signed Romneycare into law, and that he still steadfastly insists that it was, and is, a good idea? Do you not believe that they would instead put on a full-court press to convince the rest of the country that it really is only a tiny, kooky minority that wants Obamacare repealed because, after all, even when it comes to republicans, the country would only accept the one republican who not only supports a state-level version of Obamacare, he helped to bring it to life in the first place.
Vote for Romney, and Obamacare and all the rest of the socialist nanny-state is here to stay, permanently.
Quite frankly, since that is almost certain to happen, if Romney is the eventual candidate, then republicans/conservatives would be best advised to either ignore the Presidential campaign and vote only on Congressional seats, or vote for 0bama, because then at least we won't have been co-opted into the Obamacare juggernaut.