I love
Gwendolen, and I'm glad to see this spelling.
Gwendoline is interesting, but I dunno what I think about it. Although it could grow on me, my instinct is that it's contrived.
I like:
Gwendolen Aster
Gwendolen CecileGwendolen Euphémie
Gwendolen FrancesGwendolen Hesper
Gwendolen IvaGwendolen MayGwendolen PoppyGwendolen PrimroseGwendolen SusannahGwendolen SylvieGwendolen Verena