One of the most fun experiences I get to have when I run Tableau training classes is when a student comes up with a solution to a problem on their own.  Last week I was in Austin teaching a 2-day Tableau Combo class to the Facebook team there and a student was asking about relative date filters. His problem was pretty common:

1. His data is not as of today.
2. When he uses a relative date filter, he doesn't get the expected number of days in the view.

Here's a video of the problem and the solution, which uses a combination of a set and a parameter. The detailed steps are below the video.