Dahlia is fine, I think, especially if you're going with Day-lia (Dar-lia sounds a bit too lovey-dahling to me!)
Less common or Unusual names ending in a or ia. Not 'old lady' or M:
Amaya, Aliya, Anya, Aya, Ada, Aria, Alba, Aphra, Asha, Anika, Alexa, Ariana, Aurelia, Asia, Brenna, Clea, Celia, Cora, Dana, Daria, Danika, Elisa, Elina, Eliana, Fabia, Fenella, Greta, Iona, Joanna, Katya, Kyla, Lara, Lena, Luna, Livia, Leona, Larissa, Nia, Nyah, Nadia, Priya, Paloma, Rosina, Robina, Rowena, Rosalia, Ria, Saskia, Sylvia, Tamika, Thalia, Talitha, Xenia, Zia, Zelda