Data-warehousing — read about Needl's data-warehousing features and how to get your Google Analytics data into BigQuery. This capability is usually associated with Google 360 accounts and a $120K per year outlay! Needl has industry leading data-extraction technology that makes available some of the features of 360 for a small fraction of that price.
Feed client id into your Google Analytics data — make sure you set up Analytics to include a visitor tracker to future-proof your data collection. You can't do this reterospectivley so take action today!