I have learned over the past decade after working with literally thousands of otherwise intelligent people who didn't have the experience to know what handgun is best for concealed carry, that the answer is obvious. Get a .38 Special revolver. I can't tell you how many new shooters bought small and powerful, and because they didn't like the gun and couldn't hit anything with it they traded it back in. You may be a good shot and well-practiced... is your wife?
Most civilian self-defense situations will occur at close range. Pure firepower will not be an issue because the situation will be decided before more than 4 or 5 shots are fired... either you solve your problem or you miss and your problem solves you. What you need is a gun that requires very little in the way of training because it requires very little in the way of manipulation in order to be able to fire multiple shots accurately. Think of the .38 Special revolver as the gun equivalent of a point-and-shoot camera... no levers to flip, slide to bite, grip safety to depress, etc.
All of the guns you listed are nice... but unless you and your wife are willing to devote the time and money required for education, practice, and ammo, you might as well rule out any pistol and stick to the revolvers.
Smaller revolvers are nice and compact... but they kick. Unless you and your wife are willing to devote the time and money required for education, practice, and ammo, you might as well rule out the compact lightweight revolvers. They are great for self-defense in the hands of someone who can hit with them... and worse than useless if you can't hit with them because of their size or recoil.
Smith & Wesson offers the 65 (fixed sights) and 66 (adjustable sights) 3" mid-frame revolvers in stainless chambered for the .357 Magnum. These aren't much bigger than the 640 and other compact revolvers, you can shoot .38 Specials through these guns and the recoil isn't much more than a .22 revolver. I recommend the 65 with fixed sights... adjustable sights snag on stuff and adjust at the wrong time, and the fixed sight gun will be close enough out to 25 yards. Here's a gun that both you and your wife can carry and shoot, and hit something with. It's utterly reliable, and if you each shoot a box of .38s a week through the gun it will last for a decade. Best of all, if you DO shoot a box a week for a year through the gun, then you WILL have the necessary skill to adequately shoot the smaller 640 with .38s.
Taurus makes a clone of this gun in their 85 series rated for .38s only. It will also do the job.
