I think tommo has said a lot of what I would post, so I won't bore you all with a recap. Kudos to you, btw--very well put. 
But I will add a few things:Sexual identity is something that only you can really decide on. As someone told me once, "Yeah, I can decide only to date guys, but that doesn't mean I'm not attracted to women. I can't change what I want, only how I act upon those wants."
When it comes down to it, whether you call yourself bi, straight, gay, queer, opportunist, whatever label you want to adorn yourself with, however you choose to define yourself, it's a question of whether you are labeling yourself for your own self-identity, etc., purposes or for other's consumption.*smile* If you're doing it for yourself, to affirm your identity and what you want, that is great. If you're doing it for others as an easy way to let them know what category you fit in so you both know where you stand, that's great, too--both serve a purpose, the only danger is when you're so eager to fit into an easily understood category that you don't heed what you want, and you let those labels constrain what you feel you can do.
Remember, your sexuality is only one aspect of the puzzle that is you, and not the defining one unless you really want it to be so. I mean, how often do you go up to people and introduce yourself as, " Hi, I'm X, I'm a *blank*," as if all of you could be summed up in that statement, versus telling them about other aspects of yourself?
As a lesbian who has dated bisexual women, and been around others who have done the same, I'd have to say that most prejudice in the "community" seems to center around insecurities (which are certainly universal across the relationship spectrum), and around the heterosexual privilege, in terms of that option always being available, and easier in societal terms--as one person said, "It's an easy out."
What it really comes down to once you get past the LUG, or what I call "bi-tourist" years, is what you want in a relationship and in life. If what you want can't be met in a relationship with someone of a particular gender and you'll be unhappy in that "lifestyle" then it is definitely something to consider when you're getting into the relationship.
But then, how can you know if something you could get out of that relationship wouldn't be something you would need or want more?
And that, of course, is the clincher...I have to admit, I definitely have a preference for dating someone who would consider a long-term relationship with a woman in the abstract a viable option in their life, whatever our personal relationship turned out to be...but sometimes you don't really know what's possible or what you want until you've taken a chance...and that does lead to that horrible spectre of disappointment occasionally.
Going into a relationship with expectations of a happily ever after ending is not really the way to go, but having a vision of what you want or need in life and a relationship in order to be a whole and complete person is definitely something I'd recommend--whatever gender you get involved with. Sometimes, cliched as it may be, loving someone isn't enough, wanting to be with someone isn't enough.--At least, not if you don't want what comes with loving that person. It really is a package deal.
I guess the best advice I can give to anyone in this position is to keep an open mind and take everyone on a case-by-case basis and afford yourself the same generosity. After all, it's hardly as if all *insert label of choice*s are carbon copies of one another that never deviate or *gasp* change, and it's rather naive to act as if that were the case.
Don't think you have to have it all sorted out and put in a static list form with perfect spacing and capitalization before you get into a relationship, or ever, because that just isn't realistic.
*shrug* You meet someone, you're attracted, you go from there....kind of along the lines of what April said...*grin*
Best of luck.
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"She wears her wild side like a cheap perfume"-AV
