I agree with the Clary and Jace you chose but I think they should pick unknown actors for the rest of the cast :)

Here are my picks.

i like molly quinn for clary and logan lerman for simon. and scott speedman for luke.

Here are my options, hope you like them...
Clary-Molly Quinn
Jace-Alex Pettyfer
Simon-Steven R. Mcqueen
Alec-Nicholas Hoult
Isabelle-Kaya Scondelario
Luke-Gerard Butler
Valentine-Daniel Craig
Sebatian-Edward Speleers

I like Molly Quinn for Clary. I'm on the fence for the other actors.

ok so ive always wanted alex pettyfer to be jace because he is just the most perfect jace but as much as it hurts me to realize this, ive noticed its more likely that the movie makers will pick austin robert butler :( i wish soo badly that it be alex but theres that posibility now D:

:O Austin Butler as Jace???? nooooooooooooo!!!! no no no no no!!!! he's 2 wimpy 2 b my beloved Jace!! i mean i realize he may b buff but still noooo!!!! i vote for Alex Pettyfer or Chace Crawford!!! (irealize he's kinda old but he'still super sexy hottt!!!!

I really like Lily Collins for Clary but before her I was thinking:
Clary- Dani Thorne
Jace-Alex pettyfer(duh ;D)
Simon- Kristopher Turner OR Jean-Luc Bilodeau
Alec- Nicholas Hoult
Isabelle- Ashley Greene(yeah!)
Maia-Teresa Castillo OR Naomi Scott OR Maiara Walsh
Jocelyn- Bryce Dallas Howard
Maryse-Courtney Cox :))

Clary- Katherine McNamara
Jace- Dominic Sherwood
Simon- Robert Sheehan
Isabelle- Adelaide Kane
Maia- Jessica Sula
Jocelyn- Lena Headey
Maryse- Rachel Weisz
Jordan- Colton Haynes
Aline- Malese Jow
Luke- Aidan Turner
The Seelie Queen- Scarlett Johanson (with red hair)