Margot - not keen at all. Mary, Maria or Margaret are nicer, imo
Cecilia - quite like it. Also like Cecily and Celia
Cadence - really like it. But I do like the American thing. Also like the musical thing and agree Cadie is a very cute nn
Lucille - don't like this at all. I think it has an unpleasant sound.
Sylvie - quite like it. Prefer Sylvia with Sylvie as a nn
Delilah - not keen. Maybe it's the why, why, whyyyy thing, I don't know
Violet - quite like it
Lydia - quite like it
Other ideas:
Astrid, Aurora, Adele, Adeline, Adelaide, Aurelia, Beatrix, Claudia, Celeste, Cynthia, Cassandra, Daria, Dorothy, Evelyn, Elianne, Edith, Frances, Florence, Grace, Giselle, Harmony, Harriet, Honor, Iris, Ida, Irene, Josephine, Jocelyn, Joy, Judith, Julia, Juliet, Kathleen, Lillian, Lucinda, Lorelai, Larissa, Miranda, Marianne, Miriam, Nadine, Nadia, Patience, Penelope, Phoebe, Ruth, Rosemary, Rosalie, Summer, Sophia, Sorrel, Tabitha, Ursula, Winifred, Yvette