I'm not gay, nor are my feelings about this issue particularly strong. I have no intention to offend but I do plan on addressing this issue with a somewhat detached and more logical/less emotional approach.
This issue exists largely due to what I consider to be a violation of the first amendment. The institution of marriage is both a religious and legal one thus crossing the line that separates church and state. As such I believe the best way to "untangle" this issue is to leave "marriage" as a religious institution and going forward refer to all "legal marriages" as civil unions regardless of whether those unions are between two people of the same or of opposite genders.
During his first term, George W. Bush, in a move that inevitably contributed to his losing my vote to his Libertarian competitor, suggested a Constitutional Amendment defining marriage as between a man and a woman. Such an amendment would be a violation of both the 1st and 10th amendments. Defining a religious institution-- in this case marriage, is a violation of freedom of religion. The government has no place telling members of the clergy who they can and can't perform marriages for. And it would be a violation of the 10th amendment, as last I checked there is no language within the US Constitution granting the government the power to define marriage.
Leave marriage to the churches, let them sort it out for themselves.
Now on to the legal side of things... People in Civil Unions should be granted the same rights across the board regardless of the genders of the two parties in the marriage. And, in an effort to silence the "slippery slope" argument civil unions should be defined by the States (not the federal government, this again goes back to that pesky 10th amendment) as the union of two people. No inter-species unions, no polygamous unions... if one is a member of a church that recognizes polygamy that church is welcome to recognize that marriage (provided no other laws-- incest, child abuse, etc. are being broken) but the people in that "marriage" would have to realize that legally only one of the people they are married to can be recognized as their legal partner.
I know I may catch some heat for this one... and these are just ideas... they aren't fully fleshed out yet. I welcome all comments-- positive and negative. But if you're going to be negative please at least be constructive about it.