Ideally I'd want Villa to declutter and reinvest. The real time for that kind of thing is the summer window, but I think work can definitely be done.
If Vlaar is sold, I'd try and drive his price up as much as possible and invest the money in another defender and an attacking midfielder or creative striker - Villa have been crying out for a proper number 10 for the past few seasons. I wouldn't mind seeing some deadwood gone either, such as Alexander Tonev or Yacouba Sylla, could get a bit of change for them and put it towards somebody worthwhile.
What are your hopes for your club?