Designer Babies (Redux)

A couple of months ago I wrote about a story in the New York Times discussing the possibility of people with certain disabilities using prenatal genetic screening procedures to select children who shared their disability - i.e., that would "look" like them. Along those same lines, today's Times has an article about the increasingly sophisticated means of allowing couples to select the sex of their child. Right now, these methods are expensive and not available to your average couple makin' babies the "old fashioned way." Eventually, however, the technology will be more prevalent and cheaper, raising issues similar to the earlier article - Do prospective parents have the right to pick boy or girl like an option off a restaurant menu? If they do, should they? Should they give any consideration to wider societal impacts (i.e., if everybody has only girls or only boys, demographic problems quickly evolve)?