I am not sure what age child you are concerned about. I have experienced Providence High School in New Lenox, which services the far Southwest Suburbs and part of Joliet. I find it to be a very good school and a faithful school. Joliet also has Joliet Catholic High School. I don’t know anything about it really except that it has a good football team. I know that is not what you need to know about. It just happens to be all that I know about the school.
As far a elementary schools, there are many Catholic Schools and I would suggest that you have your friend visit. Mokena has St. Mary’s Elementary School and also a private Catholic School called Noonan Academy. New Lenox has St. Jude’s I believe. I haven’t met anyone that was unhappy with these schools. The suburbs all have Catholic schools. It would be a matter of visiting and having some good questions to ask. A Google search would get you to a website and from that you could begin to form an opinion.
The far southwest suburbs are growing and they are very children friendly. There are excellent park districts and schools. Most are new because the area has grown so fast. The taxes are growing also.
If your friend was not happy with their parish, there are so many to choose from that are not far away. I don’t think they will have a problem finding a faithful and strong church. It is a fairly conservative area, compared to the city. I can’t speak for the northern suburbs. but I used to live in the city and it can be very liberal. The Joliet Diocese has experienced some problems, but I find the individual parishes to be good.
I went the public school route out there, and I wouldn’t wish it on anyone!!!