Generally it's best if you think of a name and can fit a character to it. At least I think so.

The flaw in the names you have presented is that they all have the same meter. Amy, Alex, and Randi are all two syllable words with the first syllable stressed. Hyde, Crow, and King are all monosyllabic.

Experience with ethnic sounding names, but don't make them unbelievable. I think overwrought names and spellings are one of the worst thing that could happen to a person, so unless you intend to use it as a plot device or to humorous effect, act like the child's parent and keep it simple as you can.

Amy Hyde makes me think of a thin short blonde girl who is a rocker by night and a helpful perhaps librarian by day.

Alex Crow is an demi-emo punk who has changed his name to fit his new darker identity.

Randi King sounds like a slutty cheerleader. What with the randiness and all.