I have been using Mathematica since Version 1, and to me the touchstone for best practices in Mathematica is Roman Maeder's "Programming In Mathematica". It is not fair to say that PIM is dated, because every practice presented therein still works in Mathematica, which is a tribute to both Roman and Stephen. However, those of us who think of Mathematica as a programming language need instruction and guidance with the newer Paclet system, handled with the same care, completeness, and rigor that Roman gave us in PIM. Oh, and a user friendly documentation creation system, for which we are willing to wait. Briefly.
Wolfram developers: Please? Can we get "Programming in Wolfram Language"?
That said, where are the best resources currently available for best practices in Paclet authorship? Workbench and its documentation have not gotten any visible love lately. Todd Gayley's talk Paclets and Paclet Development is currently the best I have found, but it seems only an appetizer. We need something that ties the best of package development, packetizing, and distribution that Wolfram currently has to offer, including a chapter or two devoted to cloud-friendly distribution.