I really like [name_f]Estelle[/name_f] [name_m]Valentine[/name_m]! I can see why it feels playful to you, but [name_m]Valentine[/name_m] brings to mind both strength and kindness from [name_m]Valentine[/name_m] de Villefort, and strength, conviction, and integrity from St. [name_m]Valentine[/name_m]. It’s a gorgeous name that will suit your daughter well her entire life. 
I do really like [name_f]Estelle[/name_f] [name_f]Violette[/name_f] & [name_f]Estelle[/name_f] [name_f]Clementine[/name_f] from your other options, and [name_f]Simone[/name_f] and [name_f]Vivienne[/name_f] would have also been gorgeous! Here’s a few additional [name_f]French[/name_f] middles - hope this helps!
- [name_f]Estelle[/name_f] [name_m]Cecile[/name_m]
- [name_f]Estelle[/name_f] [name_f]Madeleine[/name_f]
- [name_f]Estelle[/name_f] [name_f]Odette[/name_f]
- [name_f]Estelle[/name_f] [name_f]Aurelie[/name_f]
- [name_f]Estelle[/name_f] [name_f]Amelie[/name_f]
- [name_f]Estelle[/name_f] [name_f]Philippine[/name_f]
- [name_f]Estelle[/name_f] [name_f]Celeste[/name_f]
- [name_f]Estelle[/name_f] [name_f]Felicite[/name_f]
- [name_f]Estelle[/name_f] [name_f]Josephine[/name_f]
- [name_f]Estelle[/name_f] [name_f]Liliane[/name_f]
- [name_f]Estelle[/name_f] [name_f]Eugenie[/name_f]
- [name_f]Estelle[/name_f] [name_f]Sylvie[/name_f]
- [name_f]Estelle[/name_f] [name_m]Rosamond[/name_m]
Good luck!