My first thought was Maeve too! I think it fits perfectly with your other names - the 'v' of Vale, and the more Irish-y feel of Flynn and Darby. It's gorgeous by itself, but it's a perfect match with your other names!
Some others you might consider:
Alva - I love this name, and again it fits in lovely, like Maeve it has the 'v' sound and the Irishy feel!
From the other suggestions I also like Ada and Mamie, but I can't help but adore Maeve!
Hedy / Hedi / Hedwig
To me it's unfussy, tough girl vintage. I love it!