Thank you so much for your thoughts and helpful response!! This is all so helpful, especially hearing that the flow of the first and last name work to you! I love hearing that [name_f]Isla[/name_f] and [name_f]Cecilia[/name_f] fit well and especially that you think they have a sunny, beachy, ocean vibe–we love the beach and [name_f]Hawaii[/name_f] 
[name_f][/name_f] Thank you!