Wookie, the reason Republican sex scandals are reported so well is because they're sensational. Republicans are the socially conservative party, they're the ones with members trying to introduce "family values" (the right's equivalent to political correctness), abstinence only sex education, to restrict the rights of homosexuals, etc etc. There's that and the way they used the Clinton scandal to epic proportions, so when these scandals come out there's an element of "those in glass houses shouldn't cast stones". It's also rather silly to complain about scandals being used as a political tool as if the Repubs have never done that themselves.
Examples:
- when Mark Foley gets caught harassing young male congressional pages for sex while campaigning against the sexual abuse of children and being chairman of the "House Caucus on Missing and Exploited Children", the news networks love it. It's got all the hypocrisy they need for a good scandal story.
- Larry Craig campaigned against homosexual rights and then gets caught propositioning a guy for sex in a public bathroom. (If they were to go off to a private place to continue, there'd be nothing illegal about it, so I still don't know why he was arrested, but the hypocrisy remains).
- Ted Haggard gets called out as a drug user and user of gay prostitutes, when he's been campaigning against homosexuality for years and apparently had weekly meetings/phone calls with the president.
- David Vitter gets caught using prostitutes in some bizarre case involving wearing nappies leading to a nickname amongst the prossies as "the ****ter". His wife during the Clinton scandal having joked she'd do a Lorena Bobbit on him if he did the same.
All of these have the ingredients the news channels and newspapers want.
That's why when the president of the USA gets caught getting blowjobs from someone who wasn't his wife and then lies about it under oath, the entire world hears about it for months on end.
(PS, I think the Spitzer scandal has had more of an impact than you state. Hasn't Spitzer been forced to resign over this one? In comparison Vitter and Craig remain in office.)