Edit to add (because wow this post ended up hugely long!) tldr - I'm never sure how to ID myself personally, I don't feel fully straight or bisexual. I think everything is on a sliding scale and labels should only be applied to oneself, not to others.
I actually have quite a lot of trouble trying to figure out what label I should apply to myself. I don't get hung up on it, because hey, I'm just me really and labels shouldn't matter, but it's something I've thought about from time to time.
My general feeling on any label is that you shouldn't try to apply them to other people, only to yourself. Let other people deal with their own identities, and I'll go with however they want to present themselves. I call my husband bisexual, because that is what he calls himself. Likewise with my boyfriend, who identifies as straight.
I know a lot of people who identify strongly as either straight, gay, or bisexual. I'm not sure if I know anyone in real life who identifies as pan. I definitely know a few who identify as queer, and a few trans-people.
For myself though, I'm never sure. I've never been in a relationship with a woman, although that's not saying much as I've only actually been in two relationships (the two I'm still in!). I have kissed a fair number of girls/women over the years, and slept with one. So does that make me bi?
I tend to default to ticking 'straight' on official equal opps monitoring forms because I guess maybe I don't feel 'bi enough' to identify as bisexual. More and more though, in recent years, that feels a bit like a lie. I want there to be a scale that I can put an approximate mark on! When talking to friends I think I tend to say I'm on the straight end of bi, or the bi end of straight, depending on my mood at the time.
I can certainly look at both men and women and find them physically attractive, beautiful, sexy etc. It's not always the same types either. I find lots of things attractive. I like 'girly' looking girls, I like a bit of androgyny in both genders sometimes, I like long hair on men, I quite like a bit of make-up on men (I think that's left over from my time in the goth scene) but I also like it sometimes when they are a bit scruffy and stubbly - rough & ready... It's hard to really pin down a type
I've never met a girl I wanted to have a relationship with, but that might be more a function of the fact that I'm quite picky (finding someone physically attractive doesn't necessarily mean that I want to date them!) and for ten years from the age of 18 to 28 I was monogamous with my husband so wasn't really looking, beyond going 'ooh, that person's pretty' occasionally.
When I fantasize however (in a sexual context), there are almost always women involved (as well as men - I tend to fantasize about group settings
I'm not keen on the -curious suffix, as some others have said. It sounds wishy-washy and feels very teenage to me - like girls kissing girls because it's fun and 'it doesn't really count' or something. I've heard people using heteroflexible, but that doesn't sit right with me either. I would read that as basically straight but willing to have sex with someone of the same gender, like maybe in a threesome situation.
Pansexual doesn't feel right either, but that might just be because I'm not as used to the term, having only come across it in recent years. It seems too all-encompassing. I do have physical preferences, and I think I'm somewhere towards the straight end of the scale in general, just not 100%. But then maybe it is true that I am attracted to a person simply for who they are, rather than what gender they happen to be (my husband and boyfriend are quite different, although both obviously male). Would that make me pan?
Meh, I know. I should stop fretting about labels and just be me!
Sorry for going off into extended personal musings!