I voted Ellie but I would call her Elle. Casey is too boyish for me. And Lily, well I am not feeling it.
I think of white for Lily and you said the dog is ivory. That just not compute for me. I do tend to name animals on appearance, but not always.
I have 2 dogs that are named Butters (yellow dog) and a Gracie (tri color border, she was my stumper).
I have had cats that are Smokey (grey), Bandit (black and white with triangle black patch on the eye), Stripe (from Gremlins, and yes he had a raised white mohawk on his head), Ashley (grey) and Honey (yellow tabby).