Okay, proposal ideas. Vote for one! Based strictly on what you'd want to read most, I guess.
1) A muse is tired of only inspiring others. When she asks for her own life as a human, her wish is granted -- but life as a human is more difficult than she imagined, and she learns that even if your gifts/talents aren't the ones you wanted, it doesn't mean they're not valuable. (There is also A Boy, of course, and the girl who was her charge as a muse before she became human.)
2) A (fairly spoiled, but also cynical and lonely) boy's father moves them to a house on the beach so he can (write or try photography or something). Boy is angry and resentful -- he feels like he has nothing of his own, not even his own life. (Parents are divorced, half sister and brother don't have a lot of time for him, blah blah). When he discovers a girl on the beach, he falls hard -- and then discovers she's a selkie.
3) Identical triplets are one of the star attractions of a Depression-era carnival. There's nothing actually unusual about them, despite the carnival's claims of their future-telling skills (or something like that), but some evilish person is interested in them for his own purposes. This would be a trilogy, and I'm thinking one book from each girl. (It obviously needs more thought, but I love the era and the triplet angle.)
I thought I had four, but the fourth one needs some more thinking.
So, 1, 2, 3, or tickybox? Thoughts? Help.