For those who believe "marriage is between a man and a woman."
I don't see why it matters. Makes no difference to you if a gay couple says they're in a civil union vs they're married. If they want to have a marriage, let them. There's no reason why a marriage should be so strictly limited to only straight couples, that's just a violation of individual freedoms.
The benefits of marriage are often very preferable to a civil union. It varies by state, but to be civilly united sometimes means you don't get as many legal benefits.
I know the definition of marriage says that in some jurisdictions it's specifically a man and a woman. But it shouldn't be. All around, marriage should be open to any relationship between two consenting adults.
What should gay marriage be called