I really like [name_f]Leona[/name_f] [name_f]Elizabeth[/name_f]! It has an appealing spunky sound and meaningful connections. You could use [name_f]Nonie[/name_f], [name_u]Lee[/name_u], or even [name_m]Leo[/name_m] as nicknames. [name_f]Melina[/name_f] is very pretty too. I love the nn [name_u]Mel[/name_u] for a girl.
I like many of your options! I just wanted to comment and say that [name_f]Kristen[/name_f] [name_u]Bell[/name_u]'s two daughters are [name_m]Lincoln[/name_m] and [name_f]Delta[/name_f], so personally I would steer clear of [name_f]Delta[/name_f] for your family.
With big brother [name_m]Lincoln[/name_m] I like [name_u]Aubrey[/name_u] best from your list, although I must say I prefer [name_f]Audrey[/name_f] just a bit more. [name_u]Campbell[/name_u] would be second choice!