Both are beautiful names, and I don't find either one dated.
Julia seems classic to me. I'm used to JOO-lee-a and automatically pronounce it that way because it's the typical pronunciation where I live, but YOO-lee-ah is perfectly fine.
Julia is less popular than it used to be where I live, so I don't find it all that overused for babies born these days. As for
Fiona, I can only recall meeting one. It isn't very popular where I'm at.
They would work well for siblings or separately.
Combos I would might use if I used them as first names:
Fiona Clarisse - Most likely this one.
Fiona ClaireFiona MaeveFiona Patience
Julia Simone - Most likely
Julia Simone or
Julia Corinne.
Julia CorinneJulia CeridwenJulia PatienceJulia WrenThis message was edited 1/11/2012, 6:01 AM