Since they are for the kids, Id probably go with either another 19, or a 17. The 19's can use the 17 mags, and it keeps things simple. If youre going that route, get one for yourself too.
I gave each of our boys a High Power for their first handguns, and I had one as well (still have it). HP's are great guns and good shooters, and have one of the most comfortable grips for a wide body, especially for smaller hands. Again, its also a plus when everyones guns take the same mags.
SIG's are also great guns, and the P226 is one of my favorites.