Well I don't have any kids but I'd like to comment on this.
I attended Catholic school from 1st through 12th grade. I'm so glad my parents put me through private school. I think I really benefited from it and I think I am a better person because of it. I'm not saying this to down public education. I have many friends and relatives that went to public schools that really benefited them. But I think for me, it was really a great experience. My best years are my high school years b/c I was able to be around a lot of diverse people (I attended a pre-dominantly white high school but there were a few other ethnicities besides Af-Am). It was also great b/c the class sizes were small and you were able to get a lot of personal help from teachers. I was also able to make a lot of personal friendships w/ the teachers there.
However, there were some downsides to it though. One thing was the fact that since parents paid tuition, it was kinda hard to obtain some of the things that public schools had. I'm not sure if this is true of all public schools, but from what I understand, public school students don't pay for books. Well when I was in high school, we had to pay for our books and they weren't cheap at all! I remember spending $300-400 on books in 9th and 10th grades!
Also, in high school, all the teachers taught at least 2-3 subjects. This could have been b/c my high school was very small (198 students to be exact when I was a Senior...I graduated w/ 37 people). But a lot of the subjects that I was interesting in taking, I could not b/c they didn't have someone to teach them or couldn't afford to hire someone else (unless they raised tuition which was already pretty costly).
Another thing to go along w/ this teacher thing, was that we didn't have AP courses. Apparently we had to have teachers w/ Master degrees to teach them. We almost got AP English but the teacher left the next year.
So b/c of not having advanced courses, we ended up having 6 people in my class w/ 4.0 GPAs. I think if we had AP courses, we might have been able to narrow this down a bit. I don't know if that would have worked, but it was interesting b/c we ended up having 3 Valedictorians and 3 Salutorians (I don't know how that got worked out).
But those are just some of the downs to private education. Some of my other friends who went to private schools complained of some of these things too. But these things will vary of course from school to school, just like w/ public schools. Overall, I enjoyed it and I had a lot of fun.
Sorry this was so long!