I'be had this discussion with friends, both men and women and both hetero and homo. Most straight women and gay men think a pussy is not pretty, and most straigth men and gay women think a dick is not pretty. It's all very subjective. When it's about bisexual people, it all depends on the end of the spectrum that you lean towards the most. Most bi people are not 50/50, or they would find both equally attractive. There's always a preference and it reflects, among other things, on their choice of eye candy.
As for me, as a straight guy, I do prefer the sight of a pussy. Nothing turns me on more than a pink, wet, pulsating, waxed (completely or with a small design) pussy begging to be taken care of by a vibrating tongue or a big dick.
As for other senses, the inviting smell, the sweet-and-sour taste of that wonderful fluid and the warmth feel are just plain irresistible to me.
The 1% percent gay in my profile comes from the fact that looking at other guys' dicks makes me think of my own and sex in general. I guess if I was 100% straight it wouldn't have any effect on me at all.