Question: I've been searching for a solution to this, which I thought would be trivial, and seems pretty much impossible. 

Here's the situation: I set up an AdWords campaign, ad groups and ads. I point them to www.mysite.com 

Once visitors arrive to my site through one of my ads, I want to know which exact ad they clicked on (and campaign, as apparently the ad id isn't globally unqiue). Is this possible?

I first tried by enabling Destination URL auto-tagging, but seems like the gclid parameter is pretty much useless.

Then I looked at the UTMZ cookie, but it seems like at most (correct me if this isn't the case), you get the campaign number (is this even the ID in AdWords?) and the keywords searched or the ad's keywords, one of those. Not anything I can uniquely identify the ad by, right?

Finally, I looked at ValueTrack, although again correct me if I'm wrong, but this would mean manually changing the destination URL of each of my ads in AdWords, right? Even doing this, I'm not sure I can get something that lets me uniquely identify the clicked ad. Is {creative} what I want? It's described in the docs as the "unique ID of the creative", does that mean this includes the Campaign.Id and the AdGroupAd.Id?

Thanks!

Answer: 
As far as I know there is no value track for campaign or ad group ID. You could just append something to the end of each ad's destination URL based on the campaign & ad group, but that is a bit of a chore.

If you [link your Google Analytics & AdWords accounts](https://support.google.com/adwords/answer/1704341?hl=en-GB) and use auto-tagging in AdWords you can get the information you want in GA through the AdWords report (shows campaign, ad group, keyword etc). GA is able to use the gclid to retrieve data from AdWords, and I think you can then use the GA API to get the campaign data back out if you want it.
You could:

1. turn off auto-tagging
2. pull the entire account into an excel file
3. insert a new column for each desired output variable (Campaign, ad id [like Headline?])
4. trim, lower, and find/remove spaces from the target columns (so something like: campaignname, compressedheadline)
5. then concatenate that column with your destination URLs and a UTM string like this:
?utm\_source=google&utm\_medium=ppc&utm\_content=compressedheadline&utm\_campaign=campaignname
6. use this function and replace with the appropriate columns
=concatenate([dest url column],"?utm\_source=google&utm\_medium=ppc&utm\_content=",[compressedheadline column],"&utm\_campaign=",[campaignname column])
7. if the functions for the parts between the quotes break the formula, paste them into their own cells and then reference the cells in the concatenate function.
8. Drag this formula down the entire account,
9. Copy / Paste Special / Paste Values of the new Destination URLs over the old Destination URLs.
10. Remove unnecessary columns that have been created between Campaign, Ad Group, Headline, Description Line 1, Description Line 2, Display URL and your new Destination URL.
11. Then highlight just the Campaign, Ad Group, Headline, Description Line 1, Description Line 2, Display URL and your new Destination URL and you can paste this into the AdWords Editor under "add/update multiple ads.