I need to respond. My feelings of the real reason people choose public over catholic aside, I believe the catholic school education is much better than you can get in a comperable public school, and much better than ccd. In our diocese, sacrament prep must be done as a group with the ccd folks. The kids in our school report that they already know all of the information, and the sac. prep. courses are boring, as they know it already, where the ccd kids do not.
My 3 yr old is in pre k 3. He knows what to do at church, knows how to say grace, make the sign of the cross, where the holy water is, to kneel upon entering church, etc. That is from school. You could not get that from ccd.
My 6 yr old, in kindergarten, knows the rosary, insists on grace at dinner, insists on the advent wreath, knows there should not be meat on Friday, etc. Only in a catholic school. ccd is once a week. catholic school is 8 hours a day, with reinforced values, prayers on the walls, etc. ccd is only one hour a week. My six year old is more comfortable in church, and is comfortable saying the prayers, than a cousin of his who is double his age, and goes to ccd.
Finally, I want my kids to be in a sheltered environment. They will grow up soon enough. I was parish school through grade 5, all boys with the Brothers of Mary from 6-12, then on to a (co-ed)university they run for another 7. I really did not need to be exposed to the "real world", and, neither will my children, even if it means no vacation, less house, whatever.