There's also the Coverdell plan that allows distributions for educational expenses before college. But your son may resent that you are using "his money" to pay for his cafeteria lunches in high school (or whatever expense you see fit to use it on that is allowed).
I don't have children yet, but the plan is to generously fund 529s, and then allocate them as needed. Should all my children decline to pursue higher education (statistically very unlikely), then the lax rules regarding transfers will allow some wealth redistribution among cousins, nieces and nephews, or even skip a generation, etc. Educational rebels can receive cash gifts in lieu of college tuition from elsewhere in the portfolio.
The main advantage that I see in having a dedicated college fund is that it creates an easy alternative for relatives to give to, instead of showering the kids with plastic toys for their birthdays.
Like Frs1661 pointed out, as soon as they are old enough to have earned income, they will be strongly encouraged to open their own IRA. Maybe we'll even match every dollar that they put in.