I am working on a similar dio. Its a react to an ambush. Its going to be about 4 feet long and 1.5 feet wide. I have a horizontal road, with two Brads, an M1 and a HMMWV. They are just pulling off to engage an unseen enemy. One Brad is going to be JUST pulling off the road, the other is going to have already dropped its ramp and the dismount are exiting. The M1 is in the back just slewing its turret to the left. The HMMWV... well I haven't figured out exactly what they will be doing. There is also going to be a burned out BMP and a road sign in Arabic going to Baghdad, and perhaps a dead RPG-team, but that might make it to gory, which I want to avoid.
Here is a great site with pretty much all military hardware in existence along with the country its used in and lots of pics.
http://www.fas.org/man/index.html
Its divided into the US and everyone else.