leehbi (7/8/2016)
I actually work in marketing too. If you're dealing with the Google API's from Adwords and so forth, then you don't actually have a lot of changes there. What I do is just bring in most of everything they need or may need in the future. It all starts with a conversation as others have mentioned previously. You have to get them on board with being consistent and to be fairly honest, being I work in marketing too with data warehousing, the standard KPI's do not change that much unless you're doing something dramatically different.
Google Adwords is another source on my horizon !
Then you're pretty solid because those API's do not change all that often. The data is highly structure, but the output is JSON. The end user may change, but that's with any data source. I would surely stick to having that conversation and get them on the same page with your needs if possible. I personally run into this all the time, that's why I pull in what they ideally want and some additional metrics and dimensions from the data sources that they may want in the future.