I can only speak from my own situation, so I guess I'll just put myself right out there.
I'm a single bi momma, and have been in serious relationships with partners of both genders. I honestly can see myself forming a family with someone of either sex. I happen to be dating a het male at the moment, but this past winter and spring I was involved with a lesbian female. So that's my current scorecard, I guess.
Regardless of the gender or sexual identity of my partner, I will still always be bisexual. I will always consider myself queer. The idea that your own identity changes depending on the people around you is horrifying to me. My identity is mine... I own it, it is me. By saying that who I am is maleable based on the relationships I choose to have feels very.... invasive.
Sidenote, but related (really!!). My father, when I was 22, took me aside and told me that he felt he had done his job as my father and that he would really prefer if we would just stop the parent-child father-daughter nonsense and just live the rest of our lives as friends. While he and I have always been friends and related somewhat better on a friendship-type level than on a traditional parent-child level, that does not negate the fact that he is indeed my father and I am indeed his daughter. I refuse to give him the power over me to tangibly change my identity. He is free to stop acting like my father, but he cannot simply say "ok, I am now taking away your identity as my daughter, and from this day forward we will simply be friends, like Joe Blow down the street or Mike from the old neighborhood."
Similarly, if I settle into a long term monogomous relationship with a het male, then I cannot, will not, just shed my bisexuality. I am not bi because of who I have sex with. That's like saying that a virgin lesbian teenager isn't really lesbian because she's never had sex with a female. It feels belittling to say that your identity is based on your surroundings.
Okay, I'm going to alter something I just said. Maybe I am bi because of who I have sex with. But I am QUEER because of the lifestyle I lead, and I will lead that lifestyle regardless of who I am committed to. I am an activist, I am involved, queer rights are important to me and thus to my loved ones. I do not buy into much of what is considered traditional in regards to relationships. I am more queer than many of my traditional, conservative lesbian friends who have life partners.
If I were to marry a het male, then yes I would be afforded privilages that perhaps you are not. Of course, I am also free to reject many of those privilages, or to perhaps use those privilages as a way in to open people's eyes, to help redraw the lines of what is accepted or considered status quo. I can refuse to live the assumed life and live the (very loud, very proud) life that I want.
If I marry a lesbian female? Then I guess I use the blocks that are stacked against us to climb on, shout from the top of, rearrange, and maybe knock over.
And what if I marry a bi male, or a bi female? What if I am in a long-term poly relationship? What if I marry a transgendered male? A gender-neutraled person? Then would I pass the test of being a queer? Of labeling my family as queer?
I really do understand your OP, Kincaid, and I think that this is a very interesting thread, so I thank you for starting it. I absolutely understand the sacrifices and/or benefits that people accept as a result of their relationships. Many bi people are bi on a sexual level and not on a life level, which doesn't contribute much to eradicating the discrimination and unequality that we should all be fighting to overcome.
But to demean the validity of the lifestyles of those of us who are living, breathing, existing as queer regardless of who we fall in love with does nothing to level the playing field either. All that does is alienate queer sisters and brothers with yet more labels and differences.
I will never know what it is like to be a lesbian. I am not one. If I marry a woman, I still won't be a lesbian. I don't know what it's like to be straight, either. I'm not heterosexual. If I marry a man, I won't be straight. I do know what it's like to be queer, and even if I never have sex with or love or am loved by any man or woman again, I will still be queer.