Well I'd like some LGB romances, but I ain't up for the whole "bisexualization" process of every character. I'd like to point out a difference between Leliana and Zevran in Dragon Age: Origins. Leliana basically does nothing to acknowledge that the relationship is a same-sex one. However, Zevran brings it up about once or twice. Now, if they built on this, and gave the Female-Warden and Male-Warden romance different dynamics, it would've been really good imo. I mean some people are just bisexual, and bisexualizing everybody is sorta cheap, but from my understanding of DA:2 (haven't played it yet) there are no distinctions between all the romances, no rather the gender of your Hawke. I mean, yes, some people are just bisexual, but 6?? I'd say two is stretching it, and that for three, you'd probably have to actually have a fairly different romance between the two, depending on gender. I mean, lets say we took Thane right now, and made him bisexual. He was married to his wife (WOMAN) so you'd actually have a lot of room to make the romance between MaleShep and FemaleShep different and unique. However characters with no real interesting sexual background or history that could affect the romance, lets say Tali, Jacob, and Garrus, would probably be cheapened by a bisexualization. Now some characters, I could see this working for:
Jack- We already know her story. "Girls club" comment can be interpreted many ways. However, her survivor's guilt about fact her ex that she basically killed, and wanted to live together forever as lovers, was indeed male, could be considered as an aspect of her. She appears to be bisexual, but that could have really affected her in some way (or not, I don't claim to be a psychologist)
Miranda- She has a past with men, relieving herself sexually, but I believe it all relates to her want to be a mother. She's sterile, however, so this could have a dynamic change between the MaleShep and FemShep relationship. With FemShep, sterile or not, there obviously isn't going to be a baby made, but with MaleShep, if she were fertile, she could become pregnant. So that could be part of her mindset behind the whole relationship.
Kaidan- H know a lot of people see him as a potential bi character, for many reasons. He seems like the guy you could have MaleShep say "Why didn't you tell me about this before.", and would come back "You never asked." He has his BAaT experience with the girl Rhana that could be developed, along with the fact that he quite frankly, was in boot camp, at a relatively young age, where masculinity is the law, and gay=femininity (or at least so society holds to be), so I could see something there.
Point being, don't make them bisexual just to do it. Make them bisexual because it opens up the character, makes them unique to each separate romance between FemShep and MaleShep.