Of your names, I think Lilani and [name]Milana[/name] are the most distinctive, though I do hear “[name]Milan[/name]” in [name]Milana[/name], so I slightly prefer Lilani for Hawaiian flavor.
[name]Malia[/name]
[name]Akila[/name]
Kapua
Wila
You could use a Hawaiian flower:
Amarylla ([name]Amaryllis[/name] is a kind of giant Hawaiian lily)
Oleandra (after oleander)
[name]Ginger[/name]
Plumeria
[name]Gardenia[/name]
Protea (I think this is quite an interesting name, with its connection to the sea-god Proteus)
[name]Jasmine[/name]
Lilikoi (passion flower)
[name]Lana[/name] - sounds a lot like [name]Lana[/name]'i, the Hawaiian island.
[name]Koko[/name]- name of a Hawaiian volcano… seems pretty wearable.
I love Hawaiian names! My youngest daughter is named [name]Kalea[/name] (kuh lay uh ), which means “illustrious”. We get a lot of compliments on it.
Lilani - [name_f]Leilani[/name_f] would be better since it’s a Hawaiian name.
[name_f]Milana[/name_f] - this doesn’t look Hawaiian to me; looks like [name_u]Milan[/name_u] with an a.
[name_f]Leiana[/name_f] - this does look Hawaiian but the 3 vowels in a row might confuse most people.
[name_f]Leila[/name_f] ([name_m]Lay[/name_m]-la) - doesn’t look Hawaiian to me but maybe it is; I know a few Leilas so it seems like just a name, not specifically Hawaiian.
[name_f]Alannah[/name_f] - doesn’t look like a Hawaiian name to me but it is Hawaiian-ish; how about Hanalei instead
My favorite Hawaiian names are: [name_u]Kai[/name_u], [name_f]Noelani[/name_f], [name_f]Makani[/name_f], [name_f]Nalani[/name_f]. Leialoha is a Hawaiian name that resembles [name_f]Leiana[/name_f].