I really like
Kaia, I think it's lovely. I prefer
Kaia/ Kaiah over other spellings. I don't see it as trendy but it's deffinately close, I'd say it will get more common but probably not top 20 common. I'm pleased to say I've met 2 Kaias, one was a baby the other a little girl. Of your combos I like
Kaia Isabella and Kaya
Rose. =)