Okay so I thought I'd get a start on the Civil War piece, I'm going with number 1 there, thought it'd be the most intense and dynamic of them all. I did like 3 at one point, where Iron Man has his hand gripping Cap's throat but it's tricky to keep that momentum with the piece.
I thought 1 would work nicely because it has the movement continuing from the top left corner right through to the bottom right, that where the eye naturally runs when looking at a picture and gives it a big bonus when working with it, so I think that'll work well.
Once I've got these two meshed out I'll add more characters fighting in the back, including Spidey ;)