Before i add it to my list, is this nice or just hormones talking?
I've known a couple of Siennas over the years so this seems like a slightly unusual take on it.
I looked at the stats for its usage over the years in my country and while its never been super common, the last couple of years has seen a spike in the number of girls named Vienna. (38 since 1974 but 23 of those were in the last 5 years)