I think you're over thinking this, and I mean that in a kind way. My DH and I would only work with an agency that would allow us to pick our gender. I have two daughters from a previous marriage and in my current marriage, we were only going to adopt once and we both wanted a boy. I know it's probably not the most ethical thing to do, but thank God there are people willing to adopt and go through the homestudy, etc. to give a child a wonderful home. That's the way I look at it! We are blessed now with a beautiful biracial baby boy and my daughters are so happy to have a little brother!
Good luck to you, and don't place so much emphasis on being selective.