For those who I share my (and my family's) polyamory info with, they are very accepting. I'm just careful about who I share that information with.
I live in the USA, so there are no legal protections for polyamorous families. There are no special tax-deductions, or other considerations that are extended to two-person-couples. Socially, the majority of people would (at least in public) say we are strange, weird, or "sinful", and they would not accept our lifestyle. Legally, there are no prohibitions that we have to deal with (because we're not trying to be married to multiple partners).
There is a special spiritual dimension my family enjoys, but we're a fairly spiritual-type group of people to begin with. The support we give each other emotionally, mentally, physically (in some cases), and spiritually is amazing and I wouldn't trade it for anything. We feel very connected to each other, and that sense of community and spiritual bond that we have helps on an emotional level that I don't see in many family units elsewhere. This is just my experience with polyamory, but I hope it helps. I don't mind sharing, so don't feel bad for asking. I'm happy to share info with those who are truely interested (ie not looking to condemn me or my family, and/or get into an argument). Please, if you have other questions, feel free to ask.