I haven't done one of these in a while, but after finishing up Battlestar Galactica recently, I decided that Jamie Bamber should be playing Captain America in the movie. Although he's not blonde, that can be fixed. Bamber played Lee "Apollo" Adama who wound up being one of only two characters on that show I consistently liked throughout the series. He's got screen presence and could carry this franchise.
The biggest drawback is perhaps the fact that Bamber is British and so it might be a little weird for a British guy to be playing a walking American flag, but I kind of like irony so I'm okay with it.