I usually give my sims names that would generally be considered unusual or special in real life. My real life children have common regular names because I don't want them to constantly have to spell their names or explain them. The extraordinary names are reserved for my sims. my sims have names based on stars and constellation, book characters, mythology,... You name it.
When I don't have inspiration, I use name generators online, especially fantasy name generators. Or I end up on sites for baby names and select the more special ones from there.