For we "Civil Unions but not gay marriage" types, it would be helpful if there was a state by state collection of all the contractual obligations and rights of a marriage. This book of forms could easily be filled out by any two adults who wanted to choose to enjoy the set of legal adult to adult rights that goes along with marriage.
It would also be a good civil education project for learning / teaching what the implicit rights and duties of marriage are, and how they're duplicated explicitly by the Union Contract.
I agree that two adults who care about each other, and want to live together for the rest of their lives, should be able to fairly easily arrange their economic and care precedance affairs.
However, 'marriage' is primarily for children, followed by society, and only in third place for the couple. I oppose legalization of gay adoption, and think that all children with a homosexual parent will be at a small disadvantage in life as compared to those with married natural parents. If the children are raised by two same-sex parents, I'd suspect that they their disadvantage would be less than being raised by a single parent, which is also becoming all too prevalent.
I am especially afraid of gay marriage becoming the type of norm that allows Hate Speech laws to be used against any religion which preaches that homosexual sex is sinful / evil.
This is already happening in Europe.
Support for Civil Unions, as the non-children equivalent of marriage, seems the best long term position for Reps to take. It's certainly best for me.