Hi Brian & Bec,
Just to add up to the scenario, how are you dealing with the fact that sometime a lead will land on your Website / landing page from an ad and then will leave. THen he will come back later either by a Search or direct visit and therefor you will have lost all the information about the original visit from the ad.
I have implemented a solution to help capture multiple touches a while back back and we are now implementing it again for other Marketo clients. Have a look at the slideshare document I presented at the Marketo User Summit in 2010 and let me know if that would help you acheiving your goals. I would be verry happy to get your feedback on this kind of solution.
Josh, you probably have seen this before, but any feedback are welcome! 😉
Here is teh link to the PPT on Slideshare. IF you want to discuss this in more detail, don't hesitate to reach out to me by email at firstname.lastname@example.org.
We are doing it for another client now as well.