Model 17,18,63
For the all around target, plinker, and certainly a very comfortable gun to those trying to get the feel of a 4" revolver the model 18-2,3,4. All of the other suggestions are certainly good ones and I can attest to the three I mentioned, also a Model 63 4"and a Model 17-4 6" as I own them all. There is something very special about the action of the M18's in single of double action that I think your wife should try before jumping into a M617, I also owned the 4" barrel for a period but later sold it. I would suggest unless you already have one in mind to go online and check them out, they are not cheap in 90% + condition. I wouldn't even consider one that the seller doesn't give good detailed photos of the cylinder face so you are able to check for dry firing abuse which unfortunately is quite common on older M17 and 18's.
If you like the newer SS revolvers the M63 .22 8 round 3" is a very nice piece of work, keep in mind it won't have the smooth action of a seasoned M18. I almost purchased one before I found this old M63 N/D 4".
At the end of the day I still like the M18 for its beauty, it is the perfect model to transition into a model 15 and 19.
If you happen to look at Rugers which in my opinion are fine guns watch out for SP101 .22 8 round with the 12 or 13 pound single action trigger. They are a fine .22 if you have hands of steel. I had to let mine go after finding you can't do much to lighten the action without experiencing miss fires, but still like all Rugers built to last.
Here is my 17, 18, 63. For inexpensive fun you can't beat a .22 l/r, wish I had a few more in fact.