In general, I am not opposed to the idea. If two men find love in each other and want to share each other's life in a relationship, then by all means let them get married.
My principle objection to gay marriage is the government defining marriage part.
I think that marriage is between you, your spouse (or spouses) and your God (or Gods) and that is all.
You're a guy in love with a guy, find a pastor who thinks that God doesn't mind and have them hitch you.
Think you're man enough to handle three wives? Same same.
Just about the only place I think the gubmint should stick it's teeny head in here is for taxes. Couples should make kids so that our native culture is cultivated and passed on. Tax incentives for children are A-OK for me. I don't give two shits if the child has two mommies or three mommies and two daddies; as long as the parents rear a healthy, productive, tax-paying adult.
So, count me as opposed to a law allowed same-sex marriage and supportive of "It's none of the government's business who I love and choose to share my life with."
I would replace marriage law with marriage contracts. Real contracts with teeth and you can put whatever you want in there. We could start with what most people consider a traditional marriage, and for most that will do really. Having to go through the details of what happens if you are caught cheating, for example, might cause a few folks to decide that they don't really want to get married, and that might just be beneficial. We could also predefine what happens to property and children, including things like child support.
What about insurance you ask? Why don't the insurance companies offer family plans to same-sex couples now? Is there a law forbidding them? With all the clout the homosexual organizations have, why don't they start their own insurance company offering plans to the people they claim to want to help?