Advantages compared to what? Other options are: 1) saving outright for college the earnings are taxable 2) UTMA or Uniform Transfers To Minors Act transfer the money to children and they get control at age of majority 18-21 year of age and few little benefit unless someone sues you and their money is protected 3) Life or annuities offer some tax relief but are not generally designed to handle putting money in now and then needing it back in next 20 years 4) Real Estate purchase of house near a campus on which you may send your children could be a wiser choice but lots of other issues to address 5) Prepaid college through your State which is a cousin to the marketed 529 plans is a good choice with some lock in to costs. 529 Plans are nice estate planning tool for wealthy grandparents to fund grandchildren's educational needs. One other consideration is Educational IRA with lower limits may provide more efficient and flexible solution. Why? Educational IRA address housing and other costs in more liberal fashion and also allows for private school prior to college as well. 529 will be there as effective funding if you possibly need the money for middle school or high school. If I had more information I could render and more custom answer.
I will add one strategy we use for business owners and that is to fund a ROTH for each of the kids, regardless of your income, you can put your kids on the payroll and then move that money to a ROTH, other than the tax free growth and tax free distribution advantages, if they don't use it for college they can use it for a first home or retirement. The added benefit is the kids are likely to be at a lower tax rate than the business owner parent.