Where can I find good tile layouts for Settlers of Catan?
We use Better Settlers.


  The Better Settlers Board Generator is for use with the offline board
  game Settlers of Catan. Not only does it allow for faster game setup,
  it generates a fair and engaging game.
  
  We love playing Settlers. We've noticed that sometimes the game seems
  to be over in the first fifteen minutes--and no matter how fairly we
  try to distribute resources and probabilities during setup, natural
  bias creeps in. So we developed the Better Settlers Board Generator.
  
  The algorithm for the generator is designed to create fair play. The
  result is more riveting and engaging play.
  
  You'll have a better game of Settlers.


I have no idea what the algorithm that they use is, but in all of our games so far its worked fairly well.  There is also an android app.