I make it a point to try and visit them when I can. A couple hours in Selfridges in London, Galeries Lafayette in Paris, Stockmann in Helsinki, Nordiska Kompaniet in Stockholm or Magasin du Nord in Copenhagen will tell you something about the country you're visiting, and keep you well entertained. I never buy anything outside of maybe a snack from their over-the-top food halls (most recently Moomin-shaped-gummies in Helsinki), or a sometimes surprisingly affordable lunch at one of their lunch counters (it's hard to beat the view you get along with your lunch or apéro at the top Galeries Lafayette on their terrace).
But in any case, none of these flagships have ever seemed empty or disused. On the contrary, I'm always surprised that while I might be astounded by the prices on display, there are always hundreds of local shoppers who seem to be quite happy to pay them.