Fight for More Rights!!! (Expand Civil Unions, Leave Marriage Alone)

So Prop 8 is overturned by a judge today.  Here is my understanding on the Biblical purpose of marriage:

Marriage was originally designed, by God, for a man and a woman to be wed.   Not man-man, woman-woman, man-women, men-women, man-animal, woman-animal, etc.  In Genesis 1:18-25, God brought forth all the animals and none met the criteria.  So He then made a WOMAN, not another man, to fulfill His design for marriage.

Marriage is a covenant, sacred in nature.  As the Bible says, "They shall become one flesh." (Gen. 1:24)  Here's a link that discusses the question, "Is Marriage a Covenant?"

God talks about husbands/wives throughout the Bible.  There is no mention about husband/husband or wife/wife.  There is mention of man/man, woman/woman sexually involved, but it is an abomination (Leviticus 18:22,23).

As far as gay marriage being okay with God...my understanding of scripture does not allow for that.  My understanding is the Bible does not give any indication that choosing to be gay is okay.  I try to know right from wrong based on the Bible.  My understanding of the Bible leads me to the conclusion that homosexuality is a sin. Lord knows my sins, mistakes, screw ups, and flaws are numerous. Being gay just is not one that I struggle with.  

Switching over to our society today, disregarding any Biblical implications...

Our government has attached benefits to being "Married".  Gays have been fighting for "equal rights" compared to hetero married people.  So my question is...

...why don't they fight to expand their "Civil Union Rights"???

Why do they want Marriage as the title?  If it's due to the rights the government allows for married people, doesn't fighting for expansion of what gays already have make more sense?  Or does it come down to wanting the title of "Marriage" because you want it to be more socially acceptable?