I think the biggest problem is finding all the people you'd have to pay to get everything you wanted done. After watching this video on Hulu:
I've learned that all of this stuff (variations of genes, etc) are or will be patented by someone at some point. For example they say in the documentary that one gene that is responsible for causing breast cancer has been patented. The result of this is that every single researcher that attempts to use this gene in some way in their research TO CURE BREAST CANCER has been shut down by the people who own the patent on the gene. That is, of course, unless they pay a huge amount of money for the privilege.
But I digress... To answer your original question i would have to say that my answer is somewhat similar to levite's. I would agree that preventative measures are reasonable. If your child is to be born with a certain disability or genetic defect then i don't see why you wouldn't cure them or choose/alter the egg/sperm that avoids these things. Other things such as hair color, eye color and even the sex of the child are trivial things which don't concern me either. Even when it comes to things like faster/stronger/smarter etc I'm not concerned.
Other things like gills and such I'm not so sure about. I would rather those be something the person chooses for themselves instead of having it imposed upon them. Of course it would probably be a hell of a lot more difficult to incorporate these things into a full grown individual, but fully developed gills or extra arms aren't exactly a common trait in the human race and would most likely cause more problems than they would solve.. socially and physically.
Besides, just because a parent wants their child to grow up and be an Olympic swimmer doesn't mean that the child will want to be one when they grow up. They could deck the kid out with gills and webbed toes/feet for nothing, and those attributes could end up being a burden.
As for the evolutionary part of this i see it as inevitable. Human beings will continue to integrate technology into themselves in one form or another. Some humans may end up going a Borg-like route and other may "evolve" themselves through genetic engineering into who knows what. This kinda stuff is already happening and will continue to happen. (that is unless we blow ourselves up or some other kinda crazy crap like that.)