Try out both the 357 and the 45 at the range.
Things to look for:
1. Revolvers will fit most any one’s hands. I have had difficulty finding semis to fit my hand but I have never handled a revolver that did not fit me exactly. This is very important particularly if you and your wife are going to be using the same pistol.
2. A .45 has a much slower recoil and you will find it easier to get the barrel down for the second shot. I don’t shoot the 357 for that reason. 45 is my choice.
3. You can shoot wax bullets with a revolver but not with a semi auto. You can but it is way too much trouble. The wax bullets are accurate out to 30 feet.
4. Training with 38 special is fine in the beginning, but you and your wife need to train with the bullet you will be using in a real situation.
Good luck and have fun with you new pistol.
Thanks!