Khakis

http://www.shopstyle.com/browse?fts=khaki+wrinkle+free+pants

One thing we both noticed, is that the office seems very casual in dress - as in, most men wear Khaki pants instead of suit pants. Even the young blokes. The other option appears to be chinos (for the difference, see here: http://thegentlemanadvisor.com/2015/01/11/the-gentlemans-khaki-vs-chino/).
When commenting on this, and assuming out loud that it must be different in Washington DC, hubby was assured that it was quite normal to wear kahkis. Often, with a 'sports jacket', which seems to be a slightly more loud version of a suit jacket. Sort of makes that quote from Fight Club more understandable - "You are not your kahkis..." (edited for family viewing). If lots of men wear kahkis to work, which they do seem to, perhaps it is suggesting they are not their job?
But in Australia, where mostly the guys in my office wore suit pants ('dark slacks is another description I've heard here...), it didn't hit the same cultural reflex.