Re: James Buchanan Barnes aka The Winter Solider
I like the Winter Soldier plotline, myself, and wouldn't mind seeing it appear in the movies down the line.
You know what'd be nice? If the movie gave us Cap's origin story (which occured in 1941), then time jumped to the end of his career in WWII (sometime in 1945), with the movie focusing on his last mission before he got frozen. That'd be good, because then you leave the door open for possibly going back to WWII in future sequels.
You could either A) Set the sequels in the present, and include flashbacks to WWII, which fill in what he did from 1942-1944, or B) You can actually set the sequels entirely in WWII, during those middle years that're unaccounted for in the first movie. Not sure which would be better, but I gotta say, I'd love to see the Invaders in WWII, and a Captain America movie would be the perfect place for them to appear.