The $250K and up are not one homogeneous group. The lower end of this group benefits from normal Schedule A itemized deductions, e.g. mortgage interest, property tax, state income tax, and charitable donations. As you mention, 401(k) ($17k employee contribution limit this year), but also things like the dependent care account ($5k limit) and flexible spending account, limited usually up to $5k, dropping to $2500 in '13.
The 529 deposits are limited to the gifting limit, $13K in 2012, but one can gift up to five years' deposits up front. This isn't a tax deduction, but does pull money out of one's estate and lets it grow tax free similar to a Roth IRA. The savings from such accounts is probably in the $15k - $20K range given the 20 or so year lifetime of the account and limited deposits.
At the higher end, the folks making the news are those whose income is all considered capital gains. This applies both to hedge fund managers as well as CEOs whose compensation included large blocks of stock. This isn't a tax deduction, but it's how our system works, the taxation of capital gains vs. ordinary income.