"People need to remember that the issue isn't low fees -- it's whether the plan and the participants are receiving value for their money.... [S]ome of the most successful plans are paying money for robust participant services -- but the plan, even though it might benchmark as higher cost, is prudently managed because it is providing value beyond the cost.... [T]he greatest fiduciary liability 401k plan sponsors face ... is excessive expense ratios for investments and excessive compensation for service providers.... The best way to mitigate liability is to do a good job -- to pay attention."