Big congrats!
Some ideas:
Iris
Freya
Carys
Polly
Celeste
Isadora
Beatrix
Imogen
Mathilde
Phoebe
Lucienne
Solènne
Byrony
Tabitha
Evangeline
Rupert
Felix
Casper
Orson
Silas
Otis
Heath
Lucas
Edmund
Winston
Sebastian
Phoenix
Quinlan
Rafferty
Cyrus
Then for the middle, a short, sweet classic for a girl and longer (potentially, depending on length of first) for a boy.