Large scale modern battle map
Hmm... you may be able to re-purpose the old BattleTech maps. They are hexagon based and have large scales, mech sized, of course.
Then there are the old Hero Clix and D&D minis maps. They were usually printed, but you might be able to find some in PDF format, then just zoom in or expand in your favorite image manipulation program.
Lastly, there are tons of images and tokens and urban and rural assets lists available for the downloading. You can make your own maps, if you fancy putting in the time.