[Opinions] Re: Jean/Jeannie
Hmm. Gene at least sounds like Jean, so if you loved either Eugene or Eugenie, hated John or Jean and still wanted to honour Grandma, I suppose you could talk yourself into it. Genevieve, however, doesn't work. Jennie used to be a possible nn for Jean, Jane etc, but from there to Genevieve is a step too far.
I'd rather see a young John than yet another young Nathaniel or Alexander! John Alexander is excellent. Of your girl choices, I far prefer Naomi Jean for its freshness and positive energy. Gwyneth has a flattening effect for some reason.