I was thinking about the Cap casting last night, in my dreams, and in the shower, and I've got it. Marvel already did the storyline I'm going to suggest, in Ultimate Cap or something like that..
Cap in the 40s + Tuskeegee Airmen + WILL SMITH
Cap really is like our country's Fresh Prince. Will Smith is charismatic enough to be the guy that leads the Avengers. He looks like he could be Cap. If Marvel works in the Tuskeegee Airmen story, it'll make the story more layered and complex (the Dr. behind the project could be a Nazi sympathist who defects and gives the Nazis the techniques to create an army of supersoldiers, neutralizing Cap's physical advantages and leaving him only his wits as a weapon against the Krauts), although it might make it look like Marvel was stupidly trying to show equivalence between the US and Germany. They'd have to be careful about that. It just works. Will Smith is also a bit of a nerd, I think (look at all of the Isaac Asimov movies).
Will Smith should be, NAY, must be the FIRST AVENGER.
St00n