I always thought that if I did have this last baby (back in the days where I was 'planning' it, rather than having it sprung on me in the manner it did) I would keep the gender a surprise. It would also be the perfect ending to this 'surprise' pregnancy.
I can't wait though. The practical part of me knows a boy would be the best fit for our family. He'd slip right in with uber-male Daddy and his testosterone filled brothers, and be out riding a dirt bike before he could walk. The other part of me would love a little girl. I'm still not entirely sure why. Just 'cause.