We have four and are adopting a fifth. I think it's wonderful and has opened up a whole new world for us. I can't have any more biological children and this is my second marriage. My dh doesn't have any kids of his own but is a spectacular stepdaddy to our four (their bio dad is pretty much out of the picture). My kids are thrilled with the idea of a new baby.
Many agencies won't allow you to select a gender and sometimes doing so greatly limits the possibilities. China is a good option though - almost all girls and some excellent programs out there. Best of Luck
Martha