I love
Susanna, the 'h' seems superfluous and makes it too much like 'hannah' (which isn't a bad name at all).
I don't think people will relate it immediately to Oh
Susanna at all and kids don't need a reason to tease other kids - they'll do it if the kid is named
John or
Emily.
I like
Susanna more than
Olivia, though I very much like both names.
Susanna is a new favorite of mine, growing from my like of
Susan, then to
Suzanne and then someone on this board used a combo with
Susanna... Evening
Susanna, I think, and I thought it was gorgeous. Plus it's a family name for me so I quite like it.