.357 magnum is a good gun for sport shooting and protection and you can get them for a pretty reasonable price

I bought a Rossi .357 for about $280 new. I think that it would suit your needs rather well. My wife shots it with .38 spls in it. It has a smaller grip on it so it fits her better than it does me.
If you want something different look around for a used one maybe in 9 mm. It's not too big but not too small and she shouldn't have a problem with the recoil.

If there is a shooting range/gun shop around, they might have guns that she can try. If you can get down to Royal Oak, check with Target Sports. They rent all types of guns - listed on their website:

http://www.targetsportshooting.com/shootingrange/

Very professional, serious, and helpful.

Everyone has different experience, recoil tolerance, and abilities. My 80+ year old grandma gave up her .38S&W for a Ruger Single Six .22. May not have been optimal but it was all she could handle ... and you didn't want to be on the receiving end because she knew how to use it.

If your wife is trained in the use of semi-autos I suppose the Glock or Springfield XD in 9, .40, or .45 would be a good choice. If she and the family are not willing to put in the time or money to practice quite a bit with the pistol I would select a medium frame revolver in .357 such as the S & W 686, 586, or 19. Ruger also makes a nice pistol in this size/weight range and caliber as does Taurus although I have no experience with the latter. You guys can shoot .38 specials for practice and fun with some .357s thrown in for more power. A four inch revolver is usually easier to shoot than a 2 to 2 3/4 inch and almost as easy to hide. Grip shape matters but there are so many after market ones available that you can tailor that to the individual hand if you so desire. I would stay away from the newer titantium lightweights due to the intimidating recoil and slow repeat shots they demand. All shooters should wear ear/eye protection, not just new ones.

Autos can be tough for smaller people to be able to operate. I would recommend a .38 revolver like the cops used to carry. If you can find a .357 mag that fits everybodys hand, you could go that way. The .38 would be a entry level gun that you will love to shoot for years, and will always add value to any collection.

I forgot to mention in my previous post, go to your local pawn shop and see what they have to offer.
They always have a good selection of hand guns, especially in todays economy.

Make sure you don't pay the stated price, that's just a beginning number. Be sure and haggle the price down, you will be glad you did.

I have a .380 ACP and my wife has trouble operating the slide. Granted, it can be learned, but the short tight spring on a .380 can be difficult for a beginning shooter. That's why I mentioned a .38 revolver in my previous post. Same thing in a more simple package. I also liked the mention of a .22. Some might not like that for personal defence, but I would rather hit someone with a .22 than miss with something bigger. Plus they are excellent for range shooting (can't beat the price per round).

What you have to decide is how much her life is worth. You should spare no expense and practice often. Kimbers are moderately priced and of excellent quality. Get a stainless one in .357 Sig.