Team,

I found a few websites that compare civil unions v. "civil marriage." The first was created by the group Gay & Lesbian Advocated & Defenders and is pretty emotionally charged. I think it's a good place for reference.
http://www.massequality.org/ourwork/marriage/marriagevscivilunions.pdf

Here's another one:
http://lesbianlife.about.com/cs/wedding/a/unionvmarriage.htm

The main point is that civil unions are only recognized by the single state in which it was performed, so couples are completely exempt from the federal benefits provided by marriage.

As of now, I'm not convinced we should go the route of arguing for civil unions but not marriage. It separates gays from heterosexual couples and can be easily attacked.