Here's how I think we can satisfy everyone with a rooting interest in the Civil Unions/Gay Marriage kerfuffle in two easy steps.
Step 1: Eliminate the idea of civil marriage. From now on religious marriages only. Any religion can make it's own rules about who is allowed to wed, but religious marriages will no longer be recognized by the state, and they will no longer carry secular benefits or advantages of any kind.
Step 2: Let every American choose a buddy. It can be your wife, or your sister or your neighbor. Hell, it can even be your dog. Who you choose doesn't matter, because buddyhood won't carry any special religious or social significance. It won't mean you're sleeping together, and it won't mean that you're bound together forever in the eyes of God. It just means you're buddies.
Currently, the state takes care of married couples to the tune of over 1000 separate benefits. When my plan goes into effect, all those goodies will be given to buddies instead. Buddies will be able to visit each other in the hospital, file joint tax returns, and all the rest. The left will be satisfied because all people will be equal under the law, and the right can't complain because unlike marriage, "buddyhood" implies nothing about sexual orientation. True, the people who would like to banish all homosexuals to Mars will have to give up that particular dream, but the radicals on the left will have to surrender the idea of "Marriage." So that's a compromise, I think.
[Note: I am certain other brilliant people have already proposed this plan, though a Google search of "buddy system" turns up nothing. Links to your own solutions provided on request.]