Mia Grey is lovely imo.
Most two+ syllable girl's names would probably work:) it's a nice surname.
Matilda, Alice, Beatrix/ce, Marianne, Marina, Claudia, Emily, Philippa, Clara, Iona, Cora, Juno, Carla, Antonia, Allegra, Felicity, Miranda, Alexandra, Anna, Annabel, Ginny, Victoria, Genevieve, Georgina (I personally rather like alliterations...)
If you're concerned about popularity, I'd suggest using names.darkgreener.com (well, if you're in England or Wales).