Going back to the original question of how do we plan to do it... Our kids are 2 & 4 years old right now. We will have a pot of money for each child. The goal is to be able to fund in-state undergrad. With the right circumstances, it might fund private undergrad or grad school. Anything left over will go to future grandchildren.
At this moment in time, the total costs for Husband's alma-mater, in-state, is $31k/yr--tuition, housing, meal-plan, books, fees--slightly more than doubled what it was 20 years ago. We have to think it might double again by the time our children attend. So, that would be $240k per kid, without aid or scholarships. We want to have half in the 529s and half in taxable or ROTH or something. Now, hopefully, the costs won't double, and we'll be retired by that time, so the kids should be eligible for aid/scholarships, but... you never know.
We put $20k in the 529 the year each kid was born, and the year they were 1 for a total of $40k per kid. With compound interest, it should reach $120k by college. We'll figure out the other $120k at a later date.