I don't consider myself a superstitious person, but whenever I see
Opal, I can't help but think of the bad luck the stone apparently brings. It is a beautiful and most interesting stone and I can appreciate the name for it's unusual sound and aesthetic, but it almost seems unusable and kind of out there to me.
In regards to your combinations, and disregarding the above, I think
Opal Athena is darling, as is
Opal Rosalie.
Opal Marietta seems like a brand name to me and
Opal Anais feels a little flimsy for some reason.
Ottilie
http://www.behindthename.com/pnl/116467