Having been out to family and friends for a while now, this seems to be the easiest thing to do. While some may not understand it, most of the ones who feel this way are prepared to accept it (which I'm thankful for).
What can be awkward in this case is when talking to family on the phone, and they ask about which one I'm with at the time of calling. If whomever I'm with at the time hears this, I can't help but feel a bit embarassed for them, as it's sometimes said in a 'tired' tone.
Despite being in very liberal social circles, I don't know that many people who are poly, but all of my friends are in the know, and some have met both of my men.