I adore
Louisa. In fact, if I were to ever have another dd, her name would likely be
Louisa. Even my dh approves. ;-) The only thing we disagree on is the mn. He likes
Louisa Jane and I'm more into
Louisa Madeleine or
Louisa Marigold. I don't find it dated at all since I've only met one in my entire life (and that was last fall).
Of your list, I really like
Louisa Juliet and
Louisa Rosalie but I understand the appeal of
Louisa Jennifer. Other suggestions:
Louisa Claire and
Louisa Margaret.
Re: the nn, I'd probably go with
Lulu or just
Lou.
Lucy is a bit of a stretch but if you really like it, you might just consider
Lucy since it is a full name and it sounds great with
Juliet and
Jennifer.
Re: the alliteration with
Laura, I wouldn't worry about it. Life is too short ...