It's been a long time since I last read it, but I remember that Vonda McIntyre's Dreamsnake has a few excellent bits about non-monogamny. Also, while not perfect, I think Marion Zimmer Bradley's Darkover novels to a considerably better job than any of Heinlien's work a depicting poly - the best being The Forbidden Tower, in part because you have a protagonist who is from a non-poly culture being introduce to poly.One difficulty I've seen in that most of the fiction with polyamory in it that I've read have been has been about cultures where everyone is raised with the assumption that polyamory is normal - I love Diane Duane's series that starts with The Door Into Fire, but it largely doesn't deal with this sort of thing.Oddly, the best examples I know of for depicting polyamory in all its complexities are all fanfiction, most of which is clearly written by people who understand polyamory exceedingly well. I can provide some recommendations if you are interested.