Welcome to Manhattan! Are most of your workers coming in from the suburbs, or living in the city? Unless the event is something sudden *and* makes it unwise to go outside -- like a dirty bomb -- I'd bet that most folks from the city will want to get home pronto, so there's less need for shelter-in-place supplies. I'd also recommend getting a flat of bottled water -- the 5-gallon water-service bottles are fine if you're sheltering, but if your employees are walking home they'll need individual bottles to stay hydrated on the way.

But I agree that mini-radios would be valuable in any kind of situation, as well as the logo'd mini-flashlights someone else suggested -- especially if you're in a bigger building where little of the floor space has direct access to outside light through windows. And a stash of toilet paper never comes amiss, even outside of emergency situations.

If you're in an older building, you might want to double-check the stairways and/or fire escapes, and any doors that you'd want to use in an emergency -- sometimes they're locked for "security" reasons (despite it being illegal), or are in bad shape. Conversely, in a newer building, you may want to make a mental list of what won't work in a blackout -- e.g., auto-flush toilets & sinks.