With regards to Taylor Swift, she currently has tickets going on sale for Wembley stadium in London.
There have been about half a dozen pre sales over the last few days with general sale tomorrow.
Like with the u2 gigs they have tried pushing high priced tickets all the way to nose bleed. Also have tried selling premium packages for the impatient / wealthy fan.
In some presales it has been obvious to see certain blocks available and that they have been releasing blocks from the back first.
This is of course counter intuitive for fans although beneficial for the ticketing