I've had an issue about the whole government sanction of "marriage" vs. "civil union" thing from the beginning. Think about the term "civil union." It means literally "joining sanctioned by the secular state actor." This opposed to the traditional term "marriage" which is rooted in religious doctrine.
Every "marriage" granted by the state should be a civil union as opposed to one under the doctrine of a religious sect. My wife and I were married by a judge. I am perfectly comfortable with our marriage being termed a "civil union". The net result is that we enjoy all of the legal advantages performing the ceremony and getting the license brings.
To me, both same-sex and opposite-sex couples should be placed in the same position. That position should be the ability to obtain a civil union. I am not about to try and use state power to coerce any religion into sanctioning a coupling that they don't want to--or for that matter have the state deciding that a union is one that is sanctioned under God. Nor do I want the state to be in a position of giving out two separate licenses. Therefore, we should all have civil unions.