In my case (at least this year), with major investment projects in progress, timelines demanded by customers with no tolerance for alternative dates (and those demands agreed upon by PMs and managers), I had no real opportunity to take days off without being held accountable for work expected of me during those days.

That said, I used my full two weeks to get out of the office from mid-December through the end of the year, and ended up working through part of it anyway due to more tight deadlines I was committed to without any significant input from me.

Had I not taken the days, they would have disappeared on January first without anything in exchange. In my case, it seems to just be a lose-lose.