When you're attracted to someone and they don't know it and you don't quite want them to know it (yet), do you make an effort avoid talking about romance or sex while talking with them? Does it not affect you? Do you make effort to talk about it more? And does your gender affect your decision?
For best friends, your conversations sound very formalised.
Regarding the topic however, it's really hard to say. I'm not a guy for one thing, but I can say that if I'm romantically attracted to someone, I usually avoid talking about love, sex and all that jazz in front of them. Then again, I see girls who do it deliberately, to provoke a response from a guy. I guess a male's point of view in this matter would be more useful.
Alright, those conversation examples were a bit formalized as they came from memory and I wanted to get the point across. We also talk about mundane things like how often our cats throw up and we talk at length about personal feelings and fears and bounce things off of one another. But ultimately it doesn't matter.