Defining Partnership

Due to the personal situation of a close friend, I've been giving a lot of thought lately to the hospital visitation rights of same-sex and heterosexual, non-married partners.  As reported in the NYT several days ago, the Human Rights Campaign recently released its Healthcare Equality Index, a report on the treatment of those in the GLBT community by healthcare facilities.  The results are disheartening:  while several facilities have policies that purport to offer rights to, for example, same-sex partners in the event of one partner's medical emergency, the implementation of those policies is often botched.  As a result, in some situations even those partners with legal rights are shut out of the decision-making process with respect to their partner's treatment, and are denied access to that partner even as s/he is dying. 

If the myriad legal tools offered in the various states are insufficient to protect same-sex partners (and, by some accounts, non-married, heterosexual partners), is it time for nationwide protection?  I doubt we are going to see a change in the DOMA language anytime soon, but I'm not sure we need to go that far to solve this particular problem (although I do support same-sex marriage rights).   So, what would a partner-protection law in the healthcare context look like?  What concerns would opponents put forth that should be addressed?  And what enforcement measures should be put into place?