I think a general Ms. is appropriate for anyone, for the sake of official areas like legal document and such. Personally I don't care what I'm called. I prefer "Your Liciousness" but it hasn't caught on yet.
Seriously though, in my experience, any title for a female is going to generally associate her with assumptions of what type of male companionship she keeps. Miss means she can't get one, Mrs. means she has one and Ms. means she couldn't keep one. For a guy, Mr. is just a title of respect. No matter what females choose to be called, it will all end up about who's in (or not in) their pants.
Just my experience/thoughts/opines.