Colin Farrell- IronMan/Tony Stark- he's got the playboy/party guy thing down.
WWE's Edge- Thor- Try and tell me he wouldn't make a good Thor
Ryan Renolds- Captain America- He played the straight man in Amityville, he's built, and he's a pretty boy, and he's in his late 20's.
Sean Williams Scott- Hawkeye- Think of him in Bulletproof Monk.
Ray Park- Quicksilver- I just think these two actually look alike
Naomi Watts- Scarlett Witch- I would steer clear of the incest side of the Qsilver/Switch relationship and instead make Scarlett a little older than Quicksilver and make her almost a mother figure to him, then he still get's to act all protective of her but now it seems more like he's protecting his mother
Solei Moon-Frye- Wasp- Again, I just think she looks like what I would invision the wasp to look like... and she's hot.
Justin Bartha- Hank Pym- He has that nerdy appearance that Pym would need, but not too nerdy.
I'm sure someone will hate them but these are my choices.