For Thalia, I did some Googling a while back and a few sources said that the Greek pronunciation is:
... but this Greek spelling Θάλεια suggests that it's:
I really don't have a clue which one is right x_x
EDIT:: Then, like a lemon, I realised I could Forvo the Greek spelling. Now positive that this is right:
Like Renrose said, I knew a Greek girl (well she wasn't from Greece but she was Greek) who pronounced her name Thahl-ee-uh. That's how I've always pronounced it, and it's one of my favorites.
Thea I pronounce Thee-uh. I also like this one.
I pronounce Thea as Thee-uh
I pronounce Thalia as Tha-lee-uh (A like in apple)
I don't understand when people make the 'h' silent, surely if you don't pronounce it you don't spell it like that.
If you want Tia instead of Thea then that's the way to spell it. Thomas is a fair exception because everyone knows that is how it is spelt.