Thanks for the input, guys.
I certainly do wish we could move to another building: This one is circa 1940s, and is showing it's age.
We have a couple people on the Safety team on radios during the service, with radios with the door "Greeters" in the children's area, the second story "video cafe" and the media team running the microphones and A/V stuff. As well, we have a full compliment of smoke/fire detectors.
The exit device question was not just for fire evacuation, but for all contingencies that may require a rapid evacuation.
Anyway, I was hoping one of you guys know of some place that sold 3 story window-mountable evacuation slides like on aircraft or something along those lines. Sounds like such a critter doesn't commonly exist.