One reason why I reject the hamfisted argument that marriage is the best option for everyone, everywhere, at all times, as well as its oft-invoked corollary that none of this applies to gays, is that it's an argument that overstates our knowledge of other people's lives. In its worst form, its invoked by characters so sanctimonious that you smell the bad faith on their breath before they utter a word.
Far be it from me to say that Newt Gingrich's 1981 decision to ask his first wife for a divorce while she was in the hospital recuperating from cancer should bar him from commenting on the value of traditional marriage. But six months after the divorce was finalized, he married a new woman, Marianne Ginther, which suggests there was some infidelity involved. Then in 2000 he divorced Ginther and married a third woman with whom it turns out he'd been having an affair. That, I think, is a bit much. Then after that, he became a Catholic!
As for Guliani, I don't know how much his postion is going to help him. He's in favor of "civil unions."