I've always liked it. When I was about 6 or 7 there was a Marianne in my class at school, and she was a very pleasant person. I was sorry when she left. No clue what mn she had, if any, but she left me with a good impression which not even Sense & Sensibility could destroy!
You could build on the Frenchness of it and use Marianne Louise or Marianne Laurence or Marianne Solange. Or go retro-Anglo and try something like Marianne Dinah, Marianne Cecily, Marianne Georgina, Marianne Barbara, Marianne Clara ...