One of my biggest concerns with Brody is that he doesn't have the standard Wally look, and he doesn't have a standard Barry look either. But, I can be flexible with that stuff in most cases. And while Brody is best known for his role on the O.C., he really is a talented young actor with excellent range. I think Brody could nail the Wally West from "Born to Run" and the DCAU Wally. He can pull dramatic, emotional material with ease. And it was Brody's ability to pull off any kind of humor that helped make the O.C. huge in the first place. Goofball humor, over the top, smart ass, deadpan sarcasm, geeky remarks, you name it, he can pull it off. And while he is very far from an A-list, household name he is somewhat recognizable. I know that everyone on the hype would go see a Flash movie even if it was made with a cast of first time actors, but I think a Flash film might need a known name or two, although you can always take care of that by casting known actors in villian and supporting roles.
As for my other casting idea's, I'd have Peter Krause play an older Barry Allen, Mark Harmon as Jay Garrick, Amy Acker as Tina McGee, Moira Kelly as Iris West Allen, and Linda Park as Linda Park. I'm still trying to think of casting choices for Zoom, but thats the character I'd try to get a respected, big name actor for. If Batman Begins,TDK, and Star Trek taught me anything, it's that you don't need A-list superstar actors such as Arnold Schwarzenegger or John Travolta to create interest, you need actors who are famous for the quality of there work, like Christian Bale, Liam Neeson, Aaron Eckhart, Michael Caine, Morgan Freeman, Heath Ledger, Maggie Gyllenhaal, etc. This way, in addition to the typical buzz a comic book movie brings, it will also create a buzz about the film being true quality, and that usually equals both financial and critical success.
And about Scott Porter, I personally feel he would make a much better Barry Allen if a Flash is indeed an origin flick featuring Allen.