1) Coin cells are a) to help you find your other lights and b) to make sure you have no excuse not to have some light on you at all times.
2) Lithiums come in AA an AAA formats as well and (with some minor limitations) have the benefits of both worlds (excluding price).
3) There are plenty of multi-level 123A lights which can give you large amounts of runtime -- plenty to last through most emergencies, even with only a modest stock of spare batteries. Look at the HDS U60, SF U2, SF L1, SF L2, SF A2, etc.
4) Regardless of what format battery you choose you should have a stash of batteries to last you through the emergency you are planning. Don't assume you are going to drop by the store and pick up some batteries when there is a hurricane on. They'll be out of stock. :-s

Personally, most of my emergency stores are lithium, 123A *and* AA. Their ability to store for long periods make them ideal for this task IMO. Of course, I have several multi-level lights including a multi level 2x123A headlamp (1W LED).

-john


A sample of multi level 123A lights:
Nuwai TM-301X-3
2x123A multi level headlamp (1W LED)
HDS "EDC" Ultimate 60
SF L1
SF U2
Pierce M10
SF A2
SF L2