1. If mom and dad are not both practicing Catholics, that is a strike against you. Kids look to Dad.
2. Most of the people who put their kids in Catholic school, these days, over choosing to homeschool, leave too much up to the school. You might keep up with teaching the the Faith at home but other parents largely do not. You can't control the influence of the other kids, either. So while there are some good traditional schools, I can think of two I would use, if I had to, they aren't the best option for most.
Prayer, the sacraments, good examples, keeping the liturgical year in the home, working to build a Catholic identity, will help. Since your spouse is not Catholic be sure to try to include good Catholics who are adults in the lives of the children. A godparent or a confirmation sponsor, even a priest that knows your situation. Modern music, immodest fashion, broadcast tv all harm your children, too. Stay close to your children, for everything you take away from them, to protect them, give them other innocent freedoms. Don't make the Faith a burden or a punishment
It is true of many situations, the kids grow up in a Catholic bubble, St. Mary's or Cincinatti and the entire graduating class loses the Faith, save one or two.