Love Rosalind - very elegant, Shakespearean, with a great namesake in Scientist Franklin. Sadly I hate the sound of the nn Roz, so I don't know if I could risk it personally (the few I've met have all been known as Roz rather than the full version). But if you don't mind that nn, then I'd go for it!
Sarah is very pretty and so classic. But you may need to consider whether your DD could think it's more a "Mum" name or not (because it was so hugely popular in the 70's, 80's and even into the early 90's that there will likely be quite a few Sarah's at the school gates).