Agreed, a pretty good summary even though we are on opposite sides of this. I also think the main reason he is gaining in polls of late is because he is emphasizing conservative values of late. If he abandons that, I don't think he can win. After all, might as well vote Obama if you want a liberal. The three you name seems to be the choices, unless some darkhorse emerges, or name like oft mentioned Tom Ridge emerges.
I think Romney would be his best choice, and one I favor, but somehow I think McCain will go another way. Whatever he does, will tell us more about McCain, what he will gravitate back to, which I think his natural inclination is back to more liberal environs. Hes like a liberal horse in a conservative yoke, he wants to keep pulling free and going wild again.