Are you saying that just because you believe Kennedy will want to avoid the "endless contentious effect", or do you base you prediction in some element of law - that is to say how Kennedy sees the law? I don't necessarily care how you think Kennedy should rule, but why he'll rule the way you predict.
It just seems to me like you're projecting. I wouldn't. Kennedy's opinion in Lawrence v. Texas (worth reading, as is Scalia's dissent, where he specifically worries about the majority opinion moving us closer to homosexual marriage) is pretty telling with respect to how he views rational basis scrutiny in equal protection and due process cases. Vaughn laid out a detailed case under rational basis scrutiny (in fact he opines it - Prop 8 - doesn't even survive rational basis review), which from my study of Kennedy, will likely be enticing to him.
O'Connor wrote a separate concurring opinion in Lawrence specifically because she didn't like where the majority opinion might lead with respect to marriage - and she says so in her opinion.
Remember, this isn't about how you think or how I think, but how Kennedy thinks - and it's pretty clear that Kennedy gives great deference to rational basis scrutiny in equal protection cases.