Coinlights are a nice idea, the Inova microlights can be found for reasonable cheap, sometimes I carry a PT Pulsar II. The Countycomm lites are only a buck, and make great backup illumination. Still, neither are tough enough to take the beating my keys offer.
The 2AA is too big, even the single AAs are quite a bit thicker in the pocket than AAAs, but in a purse, a woman may not care if it's AA or AAA, AA giving you longer runtime, but not necessarily more light.
daloosh