I am going to be building a tiger reloading dio soon. Might be good for a first dio. There is tons of stuff, brass shells, crates, tamiya tank reloading crew set etc. Or maybe a panzer on the russian steppes with some troops walking around or on it.
just some ideas. it really depends on what you want. 95% of the time I get an idea for a dio, it comes from a pic. So just search around and you'll find something.