First, let me say that I have contemplated this very question many times myself without the benefit of fellow forumites to flame me

. So the conclusion I came to on my own is this: that all preparation is a tradeoff. Duh! But specifically, this means that:
add in not freaking out your co-workers (one of your criteria).
The point is, EVERY bit of preparation can be seen as foolhardy and a waste of resources!!! A bulletproof car weighs more, takes specialized maintenance, needs a bigger engine, consumes more gas, can't be taken to the local car wash... and a bulletproof car IS foolhardy until it's needed. Then it was forward thinking. The point is, to you, a car is foolhardy and a waste of resources. And in general, it is. However, isn't it foolhardy and a waste of resources to lug all this extra gear? To spend your time thinking about it? I mean, what are the chances you'll need it? Any preparation is, quite simply, doing more/expending more/wasting more resources than your fellow coworkers. So, you need to take all that into account. Now, my practical advice:
~Caches!!!! Really, there is no finer solution to what you are asking for. There is no one kit that will be optimal for all those situations, so a different kit is optimal! By having multiple caches in multiple locations, it means you can have flexibility with what situation to prepare for. Have one on the bottom floor near where you will need to evac- have it be, I dunno, a general urban survival bag that can help you get to more specialized caches. Have one in the alley near the liquor store that you would hide in if there were roving mobs of people ala Katrina. Get creative. Really, trying to carry everything ON your person in business casual is ridiculous. Maybe if your briefcase that you ALWAYS carried was a survival rig, but on your person? Pssh. What if you get mugged and they take your bag/ jacket with stuff? That's a very real possibility in terms of SHTF. So prepare for that. Best of luck.
Zero