The main thing is special offers. But I don't decide where to go because I am getting a special offer from an airline.
If I want to go to London on 20th June , I will go on the 20th June. If I get an offer from Ryanair to fly to Malta cheaply on 15th June, I won't be availing of it.
Not sure about the seats either. You can get a fair few seats for €79.
If they offered something like free cancellation of flights or if you arrive early at the airport they would put you on an earlier flight at no cost, I would certainly pay €79 a year.