Marriage is good only for state benefits, in my book. All marriage is, is a simple promise to never cheat, and always be there for your mate.
Also, in the States (and most(?) other countries), there is this thing called a Marriage License that I am opposed to getting. It was invented as a way to allow otherwise illegal marriages, and was used in places, such as the American South, as a way to limit who had the right to marry. Currently, I believe they are required in all states. I am opposed to it because the simple idea of getting one implies that I'm not allowed to be with whomever I choose, and is an insult to everyone.
I will likely never get married, so the long answer is living together.