I know Zenith is considered a unisex name for some, though personally I perceive it as 100% female. I think it is because of its similarity to [name_f]Judith[/name_f] and [name_f]Lilith[/name_f].
I love the combo [name_u]Zenith[/name_u] [name_f]Olivia[/name_f]. What would you pair with [name_u]Zenith[/name_u] for a girl?
I pronounce it ZEE-nith. I’ve also seen Zenia, though prefer Xenia and Zinnia.
Zenith [name_f]Olivia[/name_f] is cool and cute at the same time. Sweet, simple [name_f]Olivia[/name_f] balances the quirkiness of [name_u]Zenith[/name_u].
Maybe [name_u]Zenith[/name_u] [name_f]Adeline[/name_f]?
Lovely softened alternative with [name_f]Adeline[/name_f] 
I ADORE [name_u]Zenith[/name_u] [name_f]Olivia[/name_f]. What a cool and cute combo!
Zenith [name_f]Olivia[/name_f] is amazing!
Finally, somebody else with some love for [name_u]Zenith[/name_u].
I would never have paired these two but they flow nicely.
I love the previous suggestion of [name_u]Zenith[/name_u] [name_f]Adeline[/name_f]! I would go for something with soft sounds and maybe even something a bit frilly…
Zenith [name_f]Amabel[/name_f]
[name_u]Zenith[/name_u] [name_f]Amelia[/name_f]
[name_u]Zenith[/name_u] [name_f]Emmeline[/name_f]
[name_u]Zenith[/name_u] [name_f]Evelina[/name_f]
[name_u]Zenith[/name_u] [name_f]Marigold[/name_f]
[name_u]Zenith[/name_u] [name_f]Mirabel[/name_f]
[name_u]Zenith[/name_u] [name_f]Rosalie[/name_f]
I think it’s really cool. [name_u]Zenith[/name_u] gives off a cool unisex vibe, and [name_f]Olivia[/name_f] gives a feminine vibe.
Zenith is cool! Reminds me of a girl named [name_f]Tanith[/name_f] that I knew in middle school.
I’m not familiar with [name_f]Tanith[/name_f]! Like that one!
It’s cute. 
I think it’s a bad Idea to name your daughter (or son!) [name_u]Zenith[/name_u]. I think it looks and sounds strange, and people won’t know how to spell or pronounce it. I think your daughter would grow to resent you if you name her this. Unless this is for a fictional character, then go right ahead.