Haha!
I get the same vibes as you. I really love the confident, independent, sophisticated feel it gives and it isn't too frilly or manly - and as much as I love frill, I find that makes for a really fresh and cool kind of name. I also don't mind too much of a 'wild' vibe from a name, but I guess we live in different times.
Marian is pretty, but it is completely different to
Carmen. I do prefer
Carmen to
Miriam, but I can't say I'd definitely be saying the same thing if I were in the same position (time, community, religion etc) as your grandmother's parents. It's a cool story though!
I have this urge to use
Marguerite at the moment, and
Carmen Marguerite is lovely. I'm not sure if it has too much 'm'. I'm in two minds about that, and not even sure that it would bother me if it did.
Carmen Victoria grows on me the more and more I think about it.
Victoria's too popular here to ever use as first name, but it does add charm and character as a middle name too.
Carmen Penelope is charming, as is
Carmen Apolline (which is more simple and less frilly than
Apollonia and I'm thinking that might be better), and
Carmen Verity is bright and youthful.
I've always swayed between liking/indifference and dislike of
Salome because of its almost 'salami' sound, but it's nicer as a middle name and
Carmen Salome definitely grabs the eye. It's very much a statement name. I can't imagine someone called
Carmen Salome being a retiring, dull, wallflower of a person. I kind of like that :P