I much prefer
Maria, Rosemaria seems a bit strange - like the too names are stuck together due to the 'e' and they don't 'flow' (you have to say them seperately)
Rosamaria or Rosamarie would look better.
I like
Rosamund too :) - completely off topic ...
I have two friends called
Maria - one goes by
Masha (or Mashenka) and the other goes by
Mimi (far out, I know!)
alice x