Loved all your replies. You're giving me some great ideas, especially the EMT shears. I did a quick inventory of what I brought with me and realized I was more prepared than I initially thought. Most of what I list here comes from ideas I've slowly been incorporating while lurking here in the past, so you can consider yourselves great teachers.  

What I have on me:
In pockets: Fenix E05, Fox 40 whistle, Leatherman Micra (moved from checked luggage), wallet, room key.

In bookbag: a water bottle, lumbar pillow, lightweight sweatshirt, granola bar and sunflower seeds, notepad, conference handouts, Galaxy Note Tab, power cords for tablet and phone (Motorola Droid Razr), Eneloop battery charger for charging my phone if I can't find a plug, compact umbrella, bandana, Buff, writing utensils, comb, prescription medication, very small FAK.  

For this conference I could get away with wearing business casual slacks and I just bought new Doc Martins. More practical for evacuating than heels and a skirt. (And more my style.) Just wish I'd had time to break in my shoes beforehand.

What I wish I had in my bookbag right now:
Heavier sweatshirt/sweater
Favorite multitool (Leatherman Wave)
Extra pair of contacts or my glasses
Extra pair Thorlos hiking socks
Poncho or garbage bag  

I know there are other things to consider and I'll be rethinking how I pack and making some changes based on your suggestions for my next conference. I'm very glad the toxic train derailment didn't force me to learn the hard way, but it sure got me thinking about other possibilities. Will be looking at more preparation for next time in regards to learning about the geography and climate of my destination, including locations of important buildings.

  Thanks!