I love the thought of marriage as I interpret it: A public, ceremonial, legal bond between two (or more) individuals who love and respect each other, and wish not to be parted. It seems very romantic to care for someone so much that you give them the gift of yourself, and accept the gift of themselves to you in return.
That being said, I am never going to find anyone who can put up with my ass from now until eternity, so I'm just content with the thought of it.