People do actually use some of these. From the girls' list, the most commonly-used ones are probably
Amaryllis and
Persephone (maybe
Briseis as an hon. mention), while from the boys' list,
Thaddeus and
Amadeus. Lately, in fact, a high school classmate FB posted her love of the name
Thaddeus for a potential future son (already has children
Lilliana and
Leo). Also, I saw a birth announcement for a boy with
Archimedes as a middle name. Anyway,
Cassiopeia seems like it could be one of the more useable ones since one can use the nickname
Cassie.
As someone really interested in antiquities, I often discuss classical baby names with a similarly-interested friend. I think we would both like almost any of these names. On a side note, I believe said friend has actually encountered people with names like
Elektra, Agamemmnon, and
Ariadne.
My personal favorites among the ancients include ones like
Hadrian and
Horatius (though I'd use the more modern
Horatio),
Hermione,
Helen, Hypatia...for some reason I really like 'h' names. However, as a manner of speaking, almost all classical names are interesting/beautiful to me.
I tend to separate Arthurian and Ancient Mediterranean names as categories of usage. Since you included those in your list, I must say that I've always favored
Percival.