I feel that eugenics so far has never offered a sensible, ethically sound alternative to natural selection. Being born and raised in the aftermath of World War II in Europe, I have seen too much of what evil can be brought on by eugenics as a doctrine, in line with what @fireinthepriory so eloquently expressed, above.
New developments may offer some scientific options for individuals, such as being able to select the gender of your child when you are known to carry a genetic illness that is gender-specific. These, however, are not eugenics from my perspective. I think it is a far cry away from parents aiming for the best possible chances for their children to people wanting to improve the race.
To improve or race through eugenics will always imply intolerable, unethical consequences, I fear. The doctrine of eugenics implies restriction of and meddling with reproductive rights of many individuals.
A free choice to (try to) reproduce or not and with a free choice of partner is a fundamental human right, as is the right to live for whoever has been born. These rights are so fundamental that giving these up to improve our race, is like giving up our humanity in order to become better humans.
It is interesting to note that in many aspects, mankind has halted natural selection. For instance: we have caesarians so that we can save mothers and children; we do all we can to save small, premature children; and we help people with fertility issues to procreate. These actions are aimed at improving the options of live to individuals.