I'd have to agree that there's no need to promote any particular arrangement as the "ideal," but instead allow people to explore whatever solution is best for them.
Monogamy has always come easy to me. Now that I'm married with children, my biggest concern is not whether or not my husband is sexually faithful to me, but negotiating a balance regarding childcare, housework, social life and family income. Sometimes I'd be happy to let my husband get sex elsewhere once in a while just so I can catch up on my sleep;) But if he were to be spending his time outside the home with someone else, I would have to pick up the slack at home and that's what would make me resentful.
I love the idea of polyamory in theory, but I think that in practice it would be very challenging. It's taken me years to find one man that I'm compatible with on every level. I feel incredibly lucky to be so well-matched, and I'm a little doubtful that I'm going to run into many other people who could fit that bill. AND taking on another lover would mean that person would have to be compatible with both of us, which narrows the field even further.
Still, I'd like to be open to that possibility. The idea of a sister-wife actually has some appeal, and so does a brother-husband:) It's just that my standards are very high and we have a lot of family obligations already. It wouldn't seem fair to expect a third lover to take on the responsibilities of our family, nor would it be fair for either myself or my husband to divert our energies outside the home anymore than we already do. It's already a delicate balance but we manage it remarkably well.