This is my female cast list, I'm still working on the male one.
Varda - Eva Green (you may disagree with me on this one, but I think she's just out of this world. A true goddess!)
Yavanna - Emanuelle Beart - another true goddess
Melian - Monica Bellucci for obvious reasons
Miriel - Marion Cotillard - when in doubt always turn to the french
Indis - Diane Kruger
Luthien - very difficult cause IMO there's no one out there more beautiful than Liv Tyler, so I'll stick to Liv (plus, I can really see her as Monica Bellucci's daughter...)
Nerdanel - Angelina Jolie (she would look fierce as a redhead!)
Earwen of Alqualonde - Charlize Theron (Aeon Flux but with longer hair, anybody? To me she just fits the 'swan-maiden' profile)
Anaire - Olga Kurylenko, she's the new Bond girl (not a big role as Anaire, but I just had to throw her in there cause she's gorgeous)
Aredhel - Catherine Zeta Jones (watch both Zorro movies and you'll know what I'm talking about
Galadriel - Cate Blanchet (I'm fantasizing about a young Galadriel embodied by Clemence Poesy... They both have noses with personality:P)
Elenwe - Sienna Guillory (she played an elf before in Eragon and she just has the right physiognomy)
Idril - Scarlett Johansson (not so sure about it, but to me she's as close as you can get to the whole angelic, perfect blonde thing. Her lips are a little too big for an elf, but then again I casted Angelina as Nerdanel, so go figure...)
Elwing - Keira Knightley most definitely!
Finduilas - Natalie Portman, again most definitely
Celebrian - Naomi Watts (this was a tricky one for me, cause she has to be the missing link between Cate Blanchett and Liv Tyler, but I'm pleased with the choice)
and finally, the human ladies:
Morwen - Evangeline Lily
Rian - Kate Bosworth