I don't really care for it. I always want to pronounce it PEE oh nee and that makes me think of ponies. For a whimsical flower name I love Tansy. PeonyTherese is my fave of what you listed.
For sure! Rue is neat. Though I will say, I think of the French word for street before Rue as a plant. But I like it, it has a kind of hipster vibe to it, like an edgy nickname for Ruth or Ruby.