Hey, long imt no see/read!
I'm usually a strong supporter of states rights, but on the subject of gay marriage, I'm one of those who definitely support a Federal Constitutional Amendment defining marriage as between a man and a woman. It then would not be a states rights issue by definition, of course.
I think if we don't add an amendment we will be asking for serious "constitutional" trouble (rather "judicial activist" trouble). Full Faith and credit will be be used "successfully" by leftist judges to override state bans, etc.
Also, our cultural decline will go into an even faster nosedive without an amendment.