this is one of those delemas...main, 1st rule of a gunfight is to have a gun and know how to use it
problem now becomes, just what is "good" enough; starting w/ caliber selection, then to the firearm it self and comfort level with it, and so on
for any carry, i'd consider a .380 at least; 9mm or .38spl would be my personal prefered minimum
h/w, as the calibers get 'bigger', in general recoil becomes greater/more felt; compound that with the weight and size of the firearm and how well it recoils in each indivdual's hand and a mild shooting .380 can become a handful in those really compact autos....
so i got several questions...why is your wife intent on an auto? why on the really small size handgun (which tends to limit caliber)? moreover, smaller autos tend to be less user friendly, less reliable w/ most loads, etc? i guess what i'm asking is why your wife would prefer a pocket sized, minimal caliber auto if she has the space for something more efficient...
since she is primarily concealing it in her purse, i'd think that a larger HG can be stored in the purse; a larger framed HG tends to take recoil better, be available in more suited cailbers, and tend to be more user friendly when shooting (therefore easier to control, manipulate, and tends to be practiced with)
to fit your criteria though, i'd consider a SW J-frame (non lightweight) or Ruger SP101 sized snubnose over those really small autos, esp due to its increased reliability; if an auto is what you are looking for, khar, keltec, the berettas, and seecamps are some to look at...
other ideas:
this topic might help:
www.ar15.com/forums/topic.html?b=5&f=4&t=48588&page=1