Hi Eric,
Agreed; that one (using PTO) is not relatable, out of the box. One common practice is to instead use a "Company Calendar" Project that effectively replaces PTO, and has other advantages.
To solve this need for one client, I created a Fairly Sophisticated solution using custom data at the user level that allowed shift coordinators to "colorize" a daily calendar for each person (e.g. o = office (green), v = vacation (purple), s = shop (yellow), f = field (blue), etc.), and then some smart reporting so that as soon as a task was assigned to an individual, the Planned Date then "turned color" according to that calendar. Works great, but not for the faint of heart.
The other option I can suggest would be a Magic Report that highlights such whoops-she's-out-of-town events by comparing PTO vs Assignments.
Regards,
Doug