We use Tableau for most of our reporting. For most of our applications, we have a direct Tableau hookup, which allows for real-time data, without any manual intervention. As you know, Workfront does not hook up to Tableau so easily. We use a manual export of Workfront to a spreadsheet, and then we use that as a datasource in Tableau.
In Workfront, make a report of every field you could possibly need in a Tableau report.
Export that report as a spreadsheet.
In Tableau, go to Data > New Data Source. Usually the second tab of the spreadsheet is cleaner than the first, so we use that one.
If you already have an existing Workfront Data Source in Tableau: Go to Data > Replace Data Source. (If your columns are named the same, your relationships with other Data Sources and calculated fields will be preserved)
It's certainly not ideal, but it's what we've got right now.