Linking Google Analytics and Google AdWords accounts used to be an amazingly frustrating effort. It once took us 2 weeks to get the right people on a web conference call, and two false starts, because a User with Account Access at the Administrative access level was needed. Back then, MCC (My Client Center) access was not good enough.
And the rule that one User with Administrative Access could only have one AdWords account meant we had to create additional brand new standalone Google Accounts just to create an AdWords Admin User so that we could link AdWords to Analytics, i.e. like this:
All those hassles are history! Gone!
MCCs can now link AdWords to Analytics, so long as the MCC signin ID has Google Analytics “Edit” privileges. And there’s no need for those extra Google Accounts created just to link AdWords and Analytics.
This has long been a frustration, as you’ll see in the search the forums:
Although this official AdWords support answer still says that a User with Administrative access is needed, this newer support answer shows how to link using MCCs.
Update: Google posted on the Inside Adwords Blog about the new Adwords Linking user interface in Google Analytics