No offense, but why would you want to give a girl the middle name "Ralph"? A lot of people don't like their middle names or are even embarrassed by them. You're going to give her one that is not only a boy's name, but also synonymous with vomiting. Please rethink this. If the name has some significance, such as being your late father's name or something, maybe change it to something that is reminiscent of that, such as Rachel, Raquel, Rafaela, etc.
As for the first name, I think Sienna is prettier.