Wasn't
Ravenna the name of the evil queen in one of the live action versions of Snow White a year or two ago? I agree that it's frilly goth, but why not use it if you and your SO really like it?
I only know girls named
Sidney, and they've never been
Sid, just
Sidney. So a boy would probably always be
Sidney.
Together, it sounds like you're a couple of world travelers.