Good examples for how to write well in TCS I was editing a student manuscript. The student remarked that it would be nice to see examples of quality writing in published work, and I realized that I couldn't really come up with good examples off the top of my head


  What are the best examples of quality mathematical writing you've seen
  ?


Rules:


I'd prefer TCS papers as far as possible. Our style is different enough from standard math papers that I think it's better to focus on TCS (also why I'm asking here and not on MO)
it would help if you mentioned what exactly you thought the paper did well. Not all exposition is good at everything - some papers have great proof outlines, some use notation really effectively and others convey intuition masterfully. 
if possible, please link to the paper. 


I'm hoping this can become a resource, like many of our other broad questions. I'm marking it CW for that reason.
In the 'Great proof outline' category, these are my favorites:

"Undirected Connectivity in Log-Space" by Omer Reingold.

"Geometry, Flows, and Graph-Partitioning Algorithms" by Sanjeev Arora, Satish Rao, and Umesh Vazirani.