I've never minded the name to be honest. Had a friend when I was quite young who was named
Casey (a girl). Other than her, I don't know that I've ever met another one. I don't mind it with a C or a K, but prefer the C spelling. I also don't find it dated.
I would choose
Casey if it were out of
Casey and
Kaylee.
Casey will suit a woman, whereas I can't really imagine a grown woman named
Kaylee. Never met a
Kaylee.