Well, you can never predict if a name is about to explode in popularity, but using an older name with strong associations that's never dropped entirely out of use might minimise the chances of it becoming too associated with a generation.
For inspiration: how about Shakespeare - Juliet, Rosalind, Celia, Jessica, Cordelia,
Or the myths: Diana, Penelope, Ariadne, Melissa, Maia, Gaia, Thalia
Or Royalty: Elizabeth, Matilda, Maud, Mary, Victoria, Louise, Isabella, Adelaide, Alice, Eugenie, Alexandra, Anne, Margaret, Catherine, Jane
Or Biblical/Saints: Helen, Agnes, Tabitha, Theresa, Talullah, Naomi, Agatha, Juliana, Apollonia, Petronilla, Marina, Felicity, Theodora, Christina, Euphemia, Pelagia, Cecilia