I'm not drawn to trendy names very often. My weakness is names that were trendy within my lifetime, or shortly before it. I think they're the worst to give to a girl - my mom gave me such a name, that sounds 20 years older than I am and I hate that a lot. So I didn't do that to my kid. I don't think it's bad to give a trendy name that will date, but it should date accurately.
I think siblings with mixtures are fine. The only time it bugs me is when there's more than one girl and they all have trendy names, but the boy is named really conservatively. "Mackenzie
, and James
," for example.