I did choose polyamory on a theoretical level first, it just made more sense to me than monogamy. My initial thought was that I would not want to deny my partners any possible sexual encounters that they might run into, and not so much of me having several partners myself.
My first ever relationship was open for outside sex or relationships but they really never occurred. After that I have been more actively looking for other partners even after finding one. At the moment am not looking for more, my two loves are enough - though am open for "metamour with benefits" -arrangement if my husband finds someone special and that is what everyone wants.
Would I change it? No, absolutely not. This is the happiest I have ever been, and to me the work keeping up all the relationships is not that difficult. Of course there is work to be done, and I have had to learn to listen better to my partners when they state their needs and emotions, but all of that is manageable. For me the extra work with the relationships is a challenge that makes life so much more fulfilling - when the problems get solved, that is. And they tend to get solved in our lives.
I am a woman with two male partners: CJ (legal husband) and Mark (no label added).