Personally I prefer [name_f]Lark[/name_f] [name_f]Seraphine[/name_f] as it is streamlined but still feminine. However in real life it would depend on the flow with the surname.
[name_f][/name_f][name_f]Lark[/name_f] [name_f]Seraphine[/name_f] [name_m]Smith[/name_m] has too many abrupt endings, so I would go with [name_f]Seraphina[/name_f]. But [name_f]Lark[/name_f] [name_f]Seraphine[/name_f] Lavoie would be absolutely stunning.