Many companies (including Google, etc.) are making healthy progress here, but nobody has managed to really tell me the incremental value of my display efforts, the value of a view-through, whether bidding on that brand term really made a difference, etc.
Right now the tools out there can give you different lenses to view data through (static/custom attribution models), or take a stab at finding a data-driven, dynamic attribution model.
However the outputs all seem to be pretty underwhelming and do not typically spit out actionable insights like "Increasing spend on X, Y and Z placements should give an incremental revenue lift of $$$$."
Companies have tried, and for the most part failed. If anyone thinks they have the solution I've been waiting for, please don't hesitate to respond. But as a starter, your offering should do more than the free version of Google Analytics.