Despite the declarations of the apocolypse put forth by opponants of SSM, Massachusetts is doing very well thank you after thousands of same sex couples tying the knot. People who are in love are now able to be happy legally. Imagine that!
Economically, states that are fighting SSM are shooting themselves in the foot. Let's face it, same sex couples bring a lot to the table. How many Boston neighborhoods have been saved from slumhood by gay couples, unconcerned by schools or vague notions of "a good place to raise your kids"?
But let's think about it beyond the same sex couples themselves, to the greater population. Allowing SSM says to the world that your state is open to new ideas, that you are not willing to let "tradition" suffocate innovation. It's not a coincidence that Massachusetts has also embraced universal health care (even if we're still working the kinks out) and green technology.
The future will win out, progress is inevitable. Without equal marriage rights, a state is hiding from progress and let me tell you, the view from the cutting edge is pretty cool.