DC, thanks again for your response and the references. But let's keep this discussion going. In the same pub you linked, see page 39 under the Tuition and Fees Deduction chapter. There, under the heading “No Double Benefit Allowed” it makes an exception for the after tax portion of the 529.
It says under that heading (third bullet) that you can’t:
“Deduct qualified education expenses that have been used to figure the tax-free portion of a distribution from a Coverdell education savings account (ESA) or a qualified tuition program (QTP). For a QTP, this applies only to the amount of tax-free earnings that were distributed, not to the recovery of contributions to the program. See Coordination With Tuition and Fees Deduction in chapter 8.
So it appears that the 529 cost basis recovery amounts (only) can also be used for the Tuition and Fees Deduction. What do you make of that? Thanks.