Recently I noticed a Facebook post from a mama friend imploring mother's of girls to stop using the word 'bossy.' She thought that it was a gender thing and that girls are negatively described "bossy" while boys displaying the same behavior are positively described as "assertive." From that perspective, I completely agree. But, that has not been my perspective. When I was growing up, all kids, boys and girls, were referred to as bossy if they tried to control play (I, myself, was a bossy girl, surprise, surprise). I tell both little boys and little girls, "you aren't the boss of anybody, s/he can play how they want!"
And remember the Kelis song several years back, "Bossy?" Being a "bossy" girl that knows what she wants and isn't afraid to tell you has been trendy for a while!
So yes, I think that if you're using the word as a negative way to separate a girl's behavior from boy's, then you need to take a look at yourself and what lessons you want your children to learn. But if you're not doing that, well, use whatever words you want (correctly, that is. mm-hmm. I'm the boss of you!).