I hadn't thought about the similarity to 'simile', so thank you for pointing it out!
Sibyl Guinevere is darling, but it's also an example of when my issues with the letter S comes into play. I don't like to see it paired with names with certain initials, most notably G, T, P, L, and F. It's a bit of an idiosyncrasy. I think if I were to have a Sybil, she'd have to be a Sybil Josephine. Cybele would allow me to be more flexible, I think.
Ottilie
http://www.behindthename.com/pnl/116467